Cost Effective Injection Molding Tips from a Design and Engineering Firm

Injection molding is one of the most popular and effective manufacturing processes, because it is capable of producing high quality parts in large numbers, and generally very quickly. In a nutshell, injection molding is when a material (generally plastic) is heated until pliable, forced into a mold made for a specific purpose, allowed to cool and harden, and then ejected from the mold. Depending on how the mold is made (and what material is being injection molded), this process can be repeated over and over in order to create large numbers of a given product. Although popular and effective, injection molding is not a cheap process; projects typically cost between $10,000 and a few hundred thousand dollars to manufacture. Let’s look at some ways to ensure that cost effective injection molding is a reality for your project.

Tips for cost effective injection molding from the Creative Mechanisms team

Make sure you’re using the right material. Did you know that there are hundreds of plastics (let alone other materials) that can be injection molded? It’s important to consider what function you want a particular piece to accomplish, and which material is most appropriate to make that happen. Does a piece need to be pliable or rigid? Will it be exposed to heat or extreme temperature deviations? How does Factor of Safety affect the materials required for design? It’s a common mistake to assume that a state-of-the-art, top-of-the-line material is the right one to utilize, but if its good qualities aren’t pertinent to your project, then they are essentially useless – and may cost more money overall. For instance, why use a 40% glass filled nylon when polyethylene would do the trick just as well? The best material for injection molding is the one that best fits your requirements and is not simply the better material overall.

Identify where processes can be consolidated. There are a lot of secondary processes involved in producing a part from scratch. Such processes (like custom inserts, label printing, painting, etc.) can prove to be time consuming, as they require extensive setup – and in injection molding, time is money. All those extra costs – and the time that could have been saved with better production management – ultimately drive the part price up. The best practice is to try to combine all of these processes into one single robust process. Read more about the Creative Mechanisms process, and how we design for defect prevention in injection molding. Core-Competencies-Injection-Molding.png

Be selective when choosing who does the injection molding.Like most industries, the injection molding industry is full of small, mid-size, and large companies. One or the other may be more appropriate depending on your project. Smaller companies will generally offer more flexibility and lower costs, whereas prices may be driven up with large companies due to higher overhead, higher salaries, and sometimes more advanced technology. In general, it’s best to choose a company that has experience molding your type of product, as it will save time during the research and development part of the project. Remember that bigger and more expensive does not necessarily equal better quality. Creative Mechanisms is not an injection molding company, but over the years, we have built a reliable network of high quality, responsive manufacturing companies that have helped to turn ideas into reality.

Consider bulk production. Molding operations are rarely personal projects or projects that will produce small numbers. In the research and development phase alone, some projects produce hundreds or thousands of prototypes, as many benefits come from extensive testing and feedback. When the product moves into the production phase, it is even more important to be able to mold as many parts in one shot as possible. Molds for production should also have as many cavities as possible without compromising the quality of the parts produced. In a competitive market, a product must be the best it can be while also being affordable. That is why it is advisable to produce as many parts as possible at one time – because it spreads the setup cost out over more parts, thus leaving you with a lower price per piece. You can now sell your product in a competitive market. 

Is the mold design optimized for cost effective injection molding? In mold design, as in bulk production, it is beneficial if you can produce as many parts as possible in a single shot. For mold design, it is also very important to be able to eject the plastic product quickly and to be ready for the next shot without wasting movements. Rods, an air blast, or a plate are typically used for the ejection stage of injection molding. Every second in the injection molding process translates into money, so it is critical to minimize the mechanisms of molding to as few and as fast as possible. A design and engineering firm that is familiar with the nuances of injection molding will create parts that will lend themselves to optimized mold design.

Optimize product design and materials. You can save a considerable amount of money, especially in material consumption, with an optimized product design. Using ribs and gussets to reinforce a product, for example, will save on material consumption, as well as ensuring that the product has uniform wall thickness that is neither too thin nor too thick. Incorporating adequate draft is also essential, as it allows for quick ejection of the product from the mold, saving time and money. If there is a need for a mechanism in the product, there are quite a few to choose from. Many can be incorporated into the molding process without the need for secondary processes or machining. Some mechanisms, such as living hinges, take advantage of the properties of the material that was used to mold the plastic part. These mechanisms can be made directly from the molding process versus spending extra time and money on other processes, such as stamping.

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Edited by Leafly Mould Provides Injection Mold, Plastic Mold, Injection Molding, Die Casting Mold, Stamping Mold

Everything You Need To Know About Injection Molding

What is Injection Molding:

Injection Molding is a manufacturing process for producing parts in large volume. It is most typically used in mass-production processes where the same part is being created thousands or even millions of times in succession.

Injection Molding Machine

Why Use Injection Molding:

The principal advantage of injection molding is the ability to scale production en masse. Once the initial costs have been paid the price per unit during injection molded manufacturing is extremely low. The price also tends to drop drastically as more parts are produced. Other advantages include the following:

  • Injection Molding produces low scrap rates relative to traditional manufacturing processes like CNC machining which cut away substantial percentages of an original plastic block or sheet. This however can be a negative relative to additive manufacturing processes like 3D printing that have even lower scrap rates. Note: waste plastic from injection molding manufacturing typically comes consistently from four areas: the sprue, the runners, the gate locations, and any overflow material that leaks out of the part cavity itself (a condition called “flash”).

Screen_Shot_2016-03-08_at_8.04.05_AM.png

Image From Ferris.edu

A sprue is simply the channel that guides molten plastic from the nozzle of the injection molding machine to the entry point for the entire injection mold tool. It is a separate part from the mold tool itself. A runner is a system of channels that meet up with the sprue, typically within or as part of the mold tool, that guides the molten plastic into the part cavities within the mold tool. There are two principal categories of runners (hot and cold) which you can read about here. Lastly, the gate is the part of the channel after the runner that leads directly into the part cavity. After an injection mold cycle (typically only seconds long) the entirety of the molten plastic will cool leaving solid plastic in the sprue, runners, gates, part cavities themselves, as well as a little bit of overflow potentially on the edges of the parts (if the seal isn’t 100% right).

Thermoset material, such as an epoxy resin that cures once exposed to air, is a material that cures and would burn after curing if one attempt is made to melt it. Thermoplastic material by contrast, is a plastic material that can be melted, cool and solidify, and then be melted again without burning. With thermoplastic materials the material can be recycled are used again. Sometimes this happens right on the factory floor. They grind up the sprues/runners and any reject parts. Then they add that material back into the raw material that goes into the injection molding press. This material is referred to as “re-grind”. Typically, quality control departments will limit the amount of regrind that is allowed to be placed back into the press. (Some performance properties of the plastic can degrade as it is molded over and over). Or, if they have a lot of it, a factory can sell this re-grind to some other factory who can use it. Typically regrind material is used for low-quality parts that don’t need high performance properties.

  • Injection Molding is very repeatable. That is, the second part you produce is going to be practically identical to the first one etc. This is a wonderful characteristic when trying to produce brand consistency and part reliability in high volume production.Injection_molding_plastic prototypes design and engineering firm

What Is The Downside To Injection Molding:

Up front costs tend to be very high due to design, testing, and tooling requirements. If you are going to produce parts in high volumes you want to make sure you get the design right the first time. That is more complicated than you might think. Getting the design right includes:

  • Designing and then prototyping the part itself to specification
    • Initial prototype development is typically completed on a 3D printer and often in a different material (such as ABS plastic) than the final part will be constructed in
  • Designing an injection mold tool for an initial production round
    • Typically generating 300-1000 injection molded prototypes in the production material requires the development of an injection mold tool.
  • Refining any and all details in the injection mold tool prior to mass-production in an injection mold manufacturing plant.

Potentially negative aspects of injection molding include the following:

  • Two of the major disadvantages to injection molding are the high tooling costs and large required lead times. Tooling is almost a project in and of itself and only one phase of the entire injection molding process. Before you can produce an injection molded part you first have to design and prototype a part (probably via CNC or 3D printing), then you have to design and prototype a mold tool that can produce replicas of the part in volume. Lastly, and typically after extensive testing in both of the aforementioned stages, you get to injection mold a part. As you can imagine, all of the iteration required to get the tool correct prior to mass production requires both time and money. It is rare that you would prototype an injection molding tool. It does happen though, especially for parts that will be made in a multi-cavity tool. For example, let’s say we were going to injection mold a new shampoo bottle cap. That cap would likely have threads to attach it to the bottle, a living hinge, a snap closure, and potentially some overmolding too. A company may choose to make a single cavity tool of that part to make sure all of the features will mold as desired. Upon approval, they will make a new tool, that is capable of molding, for example, 16 caps at a time. They do the single cavity tool first so if there are any issues, they don’t have to pay and wait for it to be fixed 16 times for each cavity.
  • Because tools are typically made out of steel (a very hard material) or aluminum it can be difficult to make changes. If you want to add plastic to the part you can always make the tool cavity larger by cutting away steel or aluminum. But if you are trying to take away plastic you need to decrease the size of the tool cavity by adding aluminum or metal to it. This is extremely difficult and in many cases might mean needing to scrap the tool (or part of the tool) entirely and start over. In other cases you might be able to weld metal into the cavity that is undesired.
  • Injection molding necessitates uniform wall thickness. If you were to cut a cross-section of the Panasonic mold above you would notice that the wall thickness is approximately 2-3mm thick throughout. Keeping walls from being too thick is important to prevent inconsistencies in the cooling process resulting in defects like sink marks. A good rule of thumb is to keep walls less than or equal to 4mm thick. The thicker the walls the more material you will use, the longer the cycle time will be and the higher your cost per part will be. Conversely, if wall thickness is any thinner than 1mm or so you might experience trouble filling the mold tool (resulting in gaps or short shots). Designers can compensate for this potentiality by using a material with a higher melt flow index like Nylon which is often suitable for walls as thin as 0.5mm. Different manufacturing techniques like CNC don’t require uniform wall thickness at all.
  • Oftentimes large parts cannot be produced via injection molding as a single piece. This is due to the size limitations of injection mold machines and the mold tools themselves. For example of a large injection molded part consider the shopping carts at Target. Although the machinery exists to mold very large pieces (e.g. 1000 ton presses roughly the size of a train’s caboose), using it is very expensive. For this reason, objects that are larger than a typical injection molding machine’s capability are most often created in multiple pieces. CNC machines have similar limitations regarding product size while 3D printing has even more limitations. CNC is limited to the travel and size of the bed in the milling machine while large 3D printed parts often need to be printed in multiple pieces and then bonded together.
  • Large undercuts require experienced design to avoid and can often add costs to the project.

What Are Some of The Considerations For Injection Molding:

Before you endeavor to produce a part via injection molding consider a few of the following things:

  1. Financial Considerations
    1. Entry Cost: Preparing a product for injection molded manufacturing requires a large initial investment. Make sure you understand this crucial point up front.
    2. Production Quantity
      1. Determine the number of parts produced at which injection molding becomes the most cost effective method of manufacturing
      2. Determine the number of parts produced at which you expect to break even on your investment (consider the costs of design, testing, production, assembly, marketing, and distribution as well as the expected price point for sales). Build in a conservative margin.
  1. Design Considerations
    1. Part Design: You want to design the part from day one with injection molding in mind. Simplifying geometry and minimizing the number of parts early on will pay dividends down the road.
    2. Tool Design: Make sure to design the mold tool to prevent defects during production. For a list of 10 common injection molding defects and how to fix or prevent them read here. Consider gate locations and run simulations using moldflow software like Solidworks Plastics.
  1. Production Considerations
    1. Cycle Time: Minimize cycle time in as much as it is possible. Using machines with hot runner technology will help as will well-thought-out tooling. Small changes can make a big difference and cutting a few seconds from your cycle time can translate into big savings when you’re producing millions of parts.
    2. Assembly: Design your part to minimize assembly. Much of the reason injection molding is done in southeast Asia is the cost of assembling simple parts during an injection molding run. To the extent that you can design assembly out of the process you will save significant money on the cost of labor.

An Example (Designing For Injection Molding)

Designing a part that’s suitable for injection molding versus one that’s suitable for machining, thermal forming, or 3D printing means taking into consideration some of the differences between the various fabrication techniques and recognizing when your project is better suited to one or the other. Typical parts you might want to injection mold include joints, brackets, or housings. For example, most consumer electronic tools are made with a plastic shell (housing) that’s injection molded and used for the body of the tool.

Consider the housing for an electric drill produced by Panasonic (see below):

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Picture courtesy of Panasonic

 

One of the most obvious advantages to injection molding is that the housing serves multiple purposes. First, it serves as a handle for the end user to interact with. It also acts as a receptacle for the battery and motor as well the location of various screw bosses that will be used to fasten the device together once the internal parts are assembled. In other words, injection molding is extremely effective when you need to organize a lot of internal parts within a housing. As a consequence, it’s a fantastic way to reduce the number of total parts (“piece count”). Of note, this part is also an overmolded part. For more on this process read here.

Some of the other reasons that injection molding is a good fit for this example include the fact that the drill is being produced in large volume. That is, Panasonic is creating a large number of copies of the same drill handle. Injection molding is wonderful for this kind of high volume production because the high initial costs pay the manufacturer back over time with low per unit costs. For this same reason injection molding can be a poor choice for low volume production. Additionally of note, there are some design constraints if using injection molding. For example, the part has nearly uniform wall thickness (which is important in order to avoid defects), and the part is made with a thermoplastic material (allowing for solid plastic stock to be repeatedly melted for the procedure). If you were designing a part with a thermoset material then injection molding would be more nuanced. You can injection mold a thermoset material but you can only do it once. Trying to melt a thermoset plastic a second time will result in burning the material. Similarly, a part with varied wall thickness would require more attention in the mold tool design to ensure uniform cooling and to avoid defects during production.

Conclusion

Injection molding is a great technology for finished production on a massive scale. It is also useful for finalized prototypes that are used for consumer and/or product testing. Prior to this late stage in production, however, 3D printing is much more affordable and flexible for products in the early stages of design.

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How Much Do Plastic Injection Molds Cost?

At least to some degree, asking what plastic injection molds cost is a lot like asking “How much is a car?”. Will your mold be a Pinto or a Porsche?

The determining factors in the cost of your mold are a combination of the part size, complexity, material, and anticipated quantities. For instance, if you wanted 1,000 washers per year, we would recommend a single cavity mold, meaning it makes one washer per machine cycle. In that case the mold would probably be $1,000-2,000.

On the other hand, if you are going to need 100,000 xbox controllers every month, we would build a 12 cavity hardened “family” mold which made four Fronts, four Backs, and four Button Trees every cycle, and you’d better have $60-$80,000 or more to invest.

Plastic Injection Mold

Of course these examples are extreme, but it illustrates the range of costs to anticipate. Your particular part will most likely fall somewhere in between that, and the molds that Rex Plastics builds average around $12,000.

Material selection is another consideration in determining what plastic injection molds cost. If your product requires a fiberglass filled material for instance, it will most likely need a mold made from hardened tool steel due to the wear those materials cause when being injected under high pressure.

If you have a target price established for your parts, it will be helpful to let your mold builder know that, because they can design the mold with that in mind, and plan for the right number of cavities to achieve that price. The more cavities (or parts made per cycle), the less expensive the parts will be, also allowing for higher output.

While you don’t need to know every detail about the types of molds available, it’s always a good idea to come prepared. Supplying the basics to your mold builder will help them build the best tool for your project. It’s also recommended that you find a mold maker who also has production capabilities. The company running the production won’t want to build an inadequate mold because they know they have to use it!

Whatever your project requires, one thing Rex Plastics won’t do is suggest you invest in a Ferrari when all you need is a Fiat!

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Edited by Leafly Mould Provides Injection Mold, Plastic Mold, Injection Molding, Die Casting Mold, Stamping Mold

Cost Effective Injection Molding Tips from a Design and Engineering Firm

Injection molding is one of the most popular and effective manufacturing processes, because it is capable of producing high quality parts in large numbers, and generally very quickly. In a nutshell, injection molding is when a material (generally plastic) is heated until pliable, forced into a mold made for a specific purpose, allowed to cool and harden, and then ejected from the mold. Depending on how the mold is made (and what material is being injection molded), this process can be repeated over and over in order to create large numbers of a given product. Although popular and effective, injection molding is not a cheap process; projects typically cost between $10,000 and a few hundred thousand dollars to manufacture. Let’s look at some ways to ensure that cost effective injection molding is a reality for your project.

Tips for cost effective injection molding 

Make sure you’re using the right material. Did you know that there are hundreds of plastics (let alone other materials) that can be injection molded? It’s important to consider what function you want a particular piece to accomplish, and which material is most appropriate to make that happen. Does a piece need to be pliable or rigid? Will it be exposed to heat or extreme temperature deviations? How does Factor of Safety affect the materials required for design? It’s a common mistake to assume that a state-of-the-art, top-of-the-line material is the right one to utilize, but if its good qualities aren’t pertinent to your project, then they are essentially useless – and may cost more money overall. For instance, why use a 40% glass filled nylon when polyethylene would do the trick just as well? The best material for injection molding is the one that best fits your requirements and is not simply the better material overall.

Identify where processes can be consolidated. There are a lot of secondary processes involved in producing a part from scratch. Such processes (like custom inserts, label printing, painting, etc.) can prove to be time consuming, as they require extensive setup – and in injection molding, time is money. All those extra costs – and the time that could have been saved with better production management – ultimately drive the part price up. The best practice is to try to combine all of these processes into one single robust process.

Be selective when choosing who does the injection molding. Like most industries, the injection molding industry is full of small, mid-size, and large companies. One or the other may be more appropriate depending on your project. Smaller companies will generally offer more flexibility and lower costs, whereas prices may be driven up with large companies due to higher overhead, higher salaries, and sometimes more advanced technology. In general, it’s best to choose a company that has experience molding your type of product, as it will save time during the research and development part of the project. Remember that bigger and more expensive does not necessarily equal better quality.

Consider bulk production. Molding operations are rarely personal projects or projects that will produce small numbers. In the research and development phase alone, some projects produce hundreds or thousands of prototypes, as many benefits come from extensive testing and feedback. When the product moves into the production phase, it is even more important to be able to mold as many parts in one shot as possible. Molds for production should also have as many cavities as possible without compromising the quality of the parts produced. In a competitive market, a product must be the best it can be while also being affordable. That is why it is advisable to produce as many parts as possible at one time – because it spreads the setup cost out over more parts, thus leaving you with a lower price per piece. You can now sell your product in a competitive market. 

Is the mold design optimized for cost effective injection molding? In mold design, as in bulk production, it is beneficial if you can produce as many parts as possible in a single shot. For mold design, it is also very important to be able to eject the plastic product quickly and to be ready for the next shot without wasting movements. Rods, an air blast, or a plate are typically used for the ejection stage of injection molding. Every second in the injection molding process translates into money, so it is critical to minimize the mechanisms of molding to as few and as fast as possible. A design and engineering firm that is familiar with the nuances of injection molding will create parts that will lend themselves to optimized mold design.

Optimize product design and materials. You can save a considerable amount of money, especially in material consumption, with an optimized product design. Using ribs and gussets to reinforce a product, for example, will save on material consumption, as well as ensuring that the product has uniform wall thickness that is neither too thin nor too thick. Incorporating adequate draft is also essential, as it allows for quick ejection of the product from the mold, saving time and money. If there is a need for a mechanism in the product, there are quite a few to choose from. Many can be incorporated into the molding process without the need for secondary processes or machining. Some mechanisms, such as living hinges, take advantage of the properties of the material that was used to mold the plastic part. These mechanisms can be made directly from the molding process versus spending extra time and money on other processes, such as stamping.

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Edited by Leafly Mould Provides Injection Mold, Plastic Mold, Injection Molding, Die Casting Mold, Stamping Mold

5 Different Design Methodologies in Solidworks

Five design features in Solidworks that every design engineer should know

Designing in Solidworks starts with a 2-dimensional sketch. From a 2D sketch one can create 3-dimensional objects using built-in tools called “features.” Features are simply different ways of converting 2D outlines into 3D objects. Two of the most common tools (methods) for doing this are extrusions (the “extrude” feature) and revolutions (the “revolve” feature).

  1. Extrusions: The Extrude feature takes a 2D sketch in the x-y plane and gives it thickness or depth by developing it linearly in the z-axis. For example, a sketch of a circle would be extruded into a cylinder. A sketch of a square would be extruded into a rectangular block (or a cube in the event the thickness were made to be the same as the x and y dimensions).
  2. Revolutions: solidworks tips for design engineersThe Revolve feature takes a 2D sketch in the x-y plane and gives it thickness or depth by rotating it about one of the two sketch axes (i.e. the x or y axis). A commonly known item that demonstrates the utility of the revolve feature is a pawn from the game of chess. An otherwise extremely intricate piece to design, the revolve feature allows the designer to develop a 2D profile which is rotated about the vertical axis for 360 degrees and easily completes the part.

Although extrusions and revolutions are some of the most common features used to design parts in Solidworks, they are nowhere near the only available options. Here are three more features that help round out a basic inventory of design tools:

  1. Sweeps: The designer can create parts using multiple sketches on perpendicular planes. One sketch will act as the profile and the other will act as the path. The profile sketch is dragged along the path to create the 3 dimensional object. The sweep feature is very effective for things like handles or pipes.solidworks tips for design engineers
  2. Surfaces and Lofts: Surfaces typically work similar to sweeps in that they utilize profile and path sketches but they also introduce guide curves. Guide curves act as a second path of sorts in the event that the surface is not going to be symmetric about the path. Surfaces are great for things like handles or nozzles. Additionally, surfaces are hollow by default (the designer simply applies a thickness to the shape which is different than most solid parts). Lofts are typically used to connect different pieces into a single part by using mathematical equations that blend the curves between parts according to the designer’s inputs.
  3. Sheet Metal: Sheet metal drawings are the most effective way to design parts that are actually manufactured by sheet metal forming (adding flanges and bends to a flat “sheet” of metal).solidworkstips.png

In truth, even these five features are only the beginning. There are a great many other tools to design and refine the design of various parts such as patterns (linear and circular are very common), holes, and a built-in toolbox for off-the-shelf (OTS) components. When determining which tools and/or features to use in your design, it is often useful to think about how the part will be fabricated once you are finished with the design. Some processes are subtractive (such as CNC), while others, like sheet metal work, manipulate a flat surface in different ways. Sometimes it is easy to buy components from manufacturers that make their Solidworks files available on the web. Sometimes parts are combined via fasteners and in other instances they might be welded together. Solidworks has powerful design tools for all of these decisions and more.

Pro Tip: Once you’ve settled on the right design, think about how you’ll display it to your clientele. What types of files do you want to export when you are finished with your design? The three most fundamental file types are .sldprt (the basic file extension for a part designed in Solidworks), .sldasm (the basic file extension for an assembly of multiple parts designed in Solidworks), and .slddwg (the basic file extension for a Solidworks drawing). But are these the right files to send to a customer?

  1. Sending files to customers: Oftentimes when we send files to a client it will be as a .STP or .STEP file. The interesting thing about this file type is that it doesn’t display the individual features that were used to build the part but rather simply displays the part as a single piece. E-drawings are another good way to send pictures or videos of the design to individuals who do not have Solidworks on their computer. Functional depictions of designs can be exported in multiple formats such as html, .exe (executable files) or .zip.
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Avoiding Design and Engineering Mistakes in Injection Molding

To bring an idea from concept to reality is no small task – ask any engineer, entrepreneur, or inventor. No matter how basic the product, there are a lot of moving parts required to get an idea designed,prototyped, and then manufactured. Avoiding costly mistakes is a must, and one of the biggest mistakes that can be made early on is poor design. A great design and engineering company can help you create a product that is designed for function, aesthetics, assembly, manufacturing, and more. Design for manufacturing is a way to minimize costly mistakes later in the production process, and there are a lot of considerations to take into account – especially when a part will be injection molded.

Injection molding is a common way to manufacture parts made from plastic, and with it comes certain considerations during the design process. In a nutshell, polymers in granule form are gravity fed through a hopper into a heating barrel, which melts the plastic. It is then forced through a nozzle under pressure and injected into a custom-made mold. The material is then allowed to cool, so that it holds its shape when ejected from the mold. Various factors will add to the complexity or cost to manufacture with injection molding, such as what material is used for the molds (steel, aluminum, beryllium copper, etc), how many cycles a mold can withstand, how long each cycle takes, whether gates are trimmed manually or automatically, and more. Injection molding is particularly suited to parts that need to be made in large quantities quickly and reliably. Let’s discuss different factors to check when a product will be injection molded so that costly mistakes are avoided.

Proper gate design, size, and location for injection molding

The gate is the opening in a mold through which molten plastic is injected under pressure. Depending on whatever piece is being created, there may be more than one gate, different types of gates, and gates in different locations. Each of these can have a positive, neutral, or negative effect on the finished piece. For instance, every type of gate will leave a mark of some sort on the part being molded – direct gates leave a large linear vestige, while hot tip gates leave a small raised blister or nub. Does it matter aesthetically or functionally if the scar is on a particular side of the completed part? Or does it need to be on the top or bottom? Poor design when it comes to gate location can result in voids or excessive sink. In addition to gate location, gate size must also be considered; larger gates permit more flow and shorter cycle time, but will also leave larger marks. Smaller gates leave a smaller vestige, but may not be ideal for proper flow and filling. Gates may be automatically or manually trimmed after the material has set. Automatic gate removal when the part is ejected from the mold avoids an additional operational step and therefore may be more cost- and time-effective, but some materials cannot withstand the shear forces required for automatic gate removal, and therefore must have the gate removed manually.

Do you have the proper wall thickness for injection molding?

When at all possible, parts should be designed with uniform wall thickness. Why? An important part of the injection mold process is when the part is cooling down, and thicker walls will take longer to cool than thinner walls. This disparity in hardening time can result in warping, cracking, or other injection molding defects, which are amplified with high shrinkage materials. (Learn about the top ten injection molding defects and how to prevent them here.) If uniform wall thickness absolutely cannot be achieved, it is possible to mitigate some adverse effects by gradually transitioning from one thickness to another. Design features like ribs and chamfers can help, as well as going back to the drawing board in general.

Design to avoid sink marks

As mentioned above, thicker parts will cool at a different rate than thinner pieces, and this can create warping, additional stress, and sink marks. The inner portion of a feature becomes insulated by the already-cooled outside, and different cooling rates mean that the inner portion will shrink inwards. This can be a difficult situation when the strength of a solid piece is required, but solid pieces that are injection molded are much more prone to developing sink marks. One way to mitigate this drawback is to core out the middle of a solid piece and reinforce it with ribs. Another is to design walls as thin as possible; thinner walls cool faster and thus decrease production time (which further decreases costs). It’s also possible to camouflage minor sink with textures…keep reading to learn more about textures.

Using textures in injection molding

As part of the manufacturing process, textures can be added to hide imperfections, increase functionality for the end user, or to lend a certain aesthetic. Texturing might include a certain finish (like gloss or matte), or actually refer to raised patterns molded into the part (crosshatching, lines, checkered, etc). Failing to factor in texturing during the design process can result in costly mistakes later, however. For instance, if a raised pattern is not accounted for during the CAD* phase of design, then ejection problems may occur if there is not enough draft factored in for a textured piece. In turn, this can result in a lot of wasted product and lost time. *Read here for Solidworks tips from the people who use it most.

Designing for stress avoidance in injection molding

To be clear, a certain amount of stress in a part is unavoidable. The very process of injection molding, in which the molecules in a resin are broken down, injected, and then allowed to harden and reform is a weakening process. For obvious reasons, it is not a good use of money to manufacture parts that are stressed to the limits of their functionality. Thankfully, there are multiple considerations throughout the manufacturing process that can counter the potential weakening associated with injection molding. First, a great design and engineering firm is going to select the proper material based on client, safety, aesthetic and functional requirements. Certain plastics are pliable, for instance, others are strong, and still others have a variety of characteristics that may be advantageous for a particular application. (To learn about various plastics commonly used in injection molding, and which might be appropriate for your own project, visit our Plastics page.) Other ways to minimize the stress built into injection molded parts are to ensure gradual transitions between different features, and to create corners that are not hard or sharp.

Be selective when choosing a design and engineering company

There is a difference between simply getting a design from a random design firm, and going to a company that has a lot of experience creating parts that will eventually be injection molded. The former route leaves much more room for error, and increases the chances that there will be a lot of back and forth between the injection molding company and the client. Conversely, design engineers who are very familiar with the injection molding process can design with the particular advantages and disadvantages of manufacturing in mind. The path from concept ideation to hitting the shelves is long and busy; it’s important to settle on the absolutely right design before going to manufacturing. To do otherwise is to lose valuable time, and like most industries, time costs money.

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Design for Affordability and Different Ways to Minimize Costs of Production

There are so many obstacles in getting a product from concept to shelves for consumer use; design, finding the right partners and funding, manufacturing costs, the validation process, competing patents, and more can all combine to make the consumer product process a fairly intimidating endeavor to undertake. That being said, billions of products have made it to market, so there are definitely chances for success. One of the ways in which we aim to help our clients is to share elements of success that we’ve gleaned from decades in design and engineering, and how to optimize for manufacturing and eventually market success!

As you might infer from above, design is a critical component of the consumer product development process, because it is really the first opportunity to create something awesome (and conversely, avoid making costly mistakes later on as a result of poor design). There are a number of objectives to prioritize when designing a part or a product, such as design for assembly, design for manufacturing, and so on. Aesthetics may be more or less important based on the specifics of the project; function is always important. In most cases, the need to design for affordability is a significant factor and an important consideration on the way to success. Let’s discuss different ways to design a part or piece for affordability.

How to design for affordability in the consumer product development process

  • Minimizing parts to the maximum extent possible. Generally, the fewer components there are in a given project, the lower the labor cost to put it together…as well as lower chances of incorrect assembly when 3 parts are used rather than 13. This also means that fewer fasteners are required. Typically, the cost savings from optimization of part assembly considerably exceed the extra costs of mold adjustments and material requirements. Use the KISS method and Keep It Simple in order to meet requirements most effectively. For instance, if snap tabs and fastener locations are done correctly, it’s possible to use only one injection molding tool for a particular assembly. Assess your design for any opportunity to combine functions and thus reduce the final number of parts required for assembly. One good way to get ideas on how to minimize parts is to look at earlier iterations of the same product. Complex tools typically have an origin as simple tools; consider simple mechanisms like levers, gears, and springs and how they may accomplish the same function that multiple parts are currently accomplishing. Bottom line: Minimizing the number of parts in a design will drive down costs, and also decrease chances of improper assembly.
  • Utilize commercial-off-the-shelf (COTS) parts as opposed to custom parts. This is an important concept for one major reason: you can leverage the work that has already been done by others in terms of capital/equipment, process development, and process validation. Consider that all of the manufacturing equipment has already been invested in, created, and tested. By using COTS equipment where possible, you can save money on costly procedures that have already been accomplished by someone else. You may pay a slightly higher price for a finished product, but it’s unlikely to be more than the costs you would incur by reinventing the wheel! Another potential downside to using COTS equipment is relying on another company’s product; it would be hard to control upward changes in price or decreased production in the future, so these are risks that need to be accounted for. Bottom line: Using COTS equipment is a smart way to leverage the capital and expertise that others have already invested.
  • Volume, volume, volume. The manufacturing process is time- and capital-intensive. One of the easiest ways to drive down cost per unit is to manufacture higher numbers…think thousands, tens of thousands, and even hundreds of thousands of parts. It is expensive to create, alter, or adjust heavy machinery (as well as the energy required to run manufacturing equipment), so it is important to get the maximum amount of use when you’re paying for time and equipment. Take the injection molding process for example. In many cases, a specific mold must be custom created, which costs money and time. The number of parts required will be a driving factor in what sort of material to use for the mold, which will also impact cost; steel molds cost more than aluminum molds, but will generally last much longer. When a product moves into the production phase, it is even more important to be able to mold as many parts in one shot as possible. Molds for production should also have as many cavities as possible without compromising the quality of the parts produced. In a competitive market, a product must be the best it can be while also being affordable. That is why it is advisable to produce as many parts as possible at one time – because it spreads the setup cost out over more parts, thus leaving you with a lower price per piece. Bottom line: Complex machinery is capital-intensive and time is money. Leverage the equipment’s capacity to make thousands of parts to drive down cost per unit. (Pro tip: Use a design and engineering company that has extensive familiarity with the manufacturing process you are going to use. This ensures that any final design is compatible with the process, and common opportunities for mistakes are mitigated.)
  • Reduce weight wherever possible. Excess material means extra cost, so this is definitely an avenue to explore during the design process. Design for affordability must be balanced with design for function – when a particular strength is required, care must be taken to achieve this functionality without also wasting material. Using ribs and gussets to reinforce a product, for example, will save on material consumption, as well as ensuring that the product has uniform wall thickness that is neither too thin nor too thick (which is an important consideration for injection molding in particular).
  • Assess which functions can be accomplished with automation rather than labor. In general, labor is expensive (especially in the United States). Design for affordability may require using manufacturing equipment that is located elsewhere in the country, or in another country entirely. This is especially true if the product is going to be distributed or sold elsewhere (to cut down on transportation and shipping costs, which must also be factored into price per unit). Design for affordability also means to seek out automated processes wherever possible.

As you can see, there are multiple ways to mitigate the costs of the manufacturing process, but this is by no means an all-inclusive list. It may not be feasible to manufacture in another country, or perhaps manual labor is required for a particular application, but there are multiple ways to design for affordability that companies, engineers, and inventors can keep in mind.

How can Creative Mechanisms assist organizations with design for affordability?

As mentioned above, design is one of the first critical points of the product development process. Of course, the concept must be a good one to begin with (read more about that here), but product design really sets the tone for success or failure. There are a few characteristics that are helpful to creating the right solution to a complex problem:

  • An environment that fosters creativity and problem-solving among a team. Creating an environment where team members can brainstorm and constantly iterate on a solution is key to success. Out-of-the-box thinking can present solutions in unexpected ways. One of the ways Creative Mechanisms fosters this environment is through our U-shaped arrangement and the way our team members interact with each other. We also take great care to hire individuals who are passionate about problem-solving and have the skills and tools necessary to innovate. You can get a better idea of this by reading some of our employee profiles (learn about Michael, Nick, and Ersen, just to name a few).
  • Expertise with computer-aided design (CAD) software. CAD is an incredibly important component of the design and engineering world. Our team has proficiency particularly with SolidWorks. We use this software to design solutions, and we then create prototypes for our clients that can be tested, evaluated, changed as necessary, and more. If you would like to learn more about using SolidWorks, read the following blogs:
    • SolidWorks Tips for Design and Engineering
    • Different Design Methodologies in SolidWorks
  • A breadth of experience. One of the characteristics that sets our team apart is the breadth of experience we’ve garnered over the years. We have created solutions for clients in the medical device, consumer products, automotive, personal care, toy industry, and more. We pride ourselves on this diversity, and our ability to transfer skills or lessons learned from one project into another. We have brought multiple products to market, and have assisted countless clients with the same. We can lend assistance as consultants, designers, model-makers, and engineers, and we are passionate about finding the best way forward for clients. But don’t take it from us – read some of the Client Testimonials we’ve collected that you can read here.
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Top 10 Reasons to Use a Professional Design and Engineering Team

Innovative companies use a variety of methods to find design and engineering success in the product development process. Some organizations have in-house designers, others use large industrial design  firms, and still others partner with small, skilled teams like we have at Creative Mechanisms. In this blog, we’ll discuss the merits of using a specialized group of design engineers for product development, as well as the benefits that that smaller firms provide.

Why you should use a design and engineering team to bring an idea from concept to reality.

  • Manufacturing costs will be lower. Every additional part in a mechanism translates into additional costs by way of extra material usage, extra manpower, and extra time to produce. Simply put, the more parts a mechanism has, the more it costs to make. One of the most apparent and immediate benefits of working with a design and engineering team is the reduction in manufacturing costs, because an experienced mechanism design team has “been there, done that” and will be able to find a simple solution that still achieves the desired result. (See some of the solutions we have come up with here.)

    In addition, every part in a mechanism is able to do only so much; known as the “part tolerance,” this must be considered when determining which parts to put together in a mechanism. Years of experience will have taught the mechanism design team which parts work together most effectively and which parts can be combined to achieve the desired motion with the simplest means. Because they have this knowledge, less time will ultimately be wasted tinkering with design options.

  • Your product will be easier to manufacture. The most elegant solution to a mechanism is the one that uses the fewest parts possible to create a series of complex motions. The elimination of excess parts reduces assembly time in addition to manufacturing costs, and it also improves the manufacturability of your mechanism. A design and engineering team must also constantly be aware of the way that the product will be physically assembled on the factory floor. The design of the assembly is just as important as the design of the mechanism, because the mechanism must be tested when it is assembled – without closing the housing. An upside down assembly in which you are able to install all the mechanical parts in the top housing is the best assembly method; your team of mechanism design specialists will be experienced in the tricks and nuances of this technique. (Read our comprehensive blogs Design for Assembly and Design for Manufacturing and Manufacturing Process Improvement.)
  • A small, highly functioning team is more nimble. Bigger is not always better. There are absolutely benefits to working with a large industrial design company, but one of the most critical components to successful product design is being quick to adapt changes and reiterate. How quickly can your design engineers go through the Design – Fail – Learn – Repeat process? The team that can iterate quickly and successfully is most likely to bring in a project on time and on budget. When you have a dynamic team that works well together, but is not burdened by the trappings of bureaucracy, then you have gained a significant advantage over your competition. At a firm like Creative Mechanisms, the sole purpose of our design team is to engineer solutions and communicate with clients…no additional duties, no red tape, and no lengthy decision-making process.
  • The odds of developing better features for your product will increase. When you approach a design and engineering team, chances are that you have one thing on your mind: getting your product to market as quickly as possible. Even if improving product design is on your mind, it’s probably not at the forefront; you’ve spent so much time working with this product that you feel like your design is finished – and now you want to make as many as possible in the least amount of time. Meeting with a group of mechanism design engineers, however, is akin to meeting with a group of muses; if you let them use their deep wells of knowledge and experience to think of new designs for your product, they might even discover that your design can do completely new functions that you never considered. If you embrace the opportunity to consult with a design and engineering team, their creativity and imagination can only heighten and improve the uniqueness and functionality of your design, especially in the conceptualization stage. Each member of the team will interpret problems differently, and these concepts can be presented to the client to create a “super” concept, which combines the best elements of multiple solutions.  Your product may have more potential than you imagined.
  • Get a better functioning design. A good design and engineering team will evaluate all the possible ways of achieving your desired function. They know more methods of achieving that function because of their experience. They have seen and made a wider variety of mechanisms simply because they do this day in and day out. They have a tried and true process for evaluating options and determining the best solution based on cost, manufacturing, reliability, consumer preference, and ergonomics.

 

  • You can shorten your time to market. A good team of specialists works so well together that your design can be passed around in such a way that the most efficient person for each stage of design and production is hard at work on that portion of the project. Having multiple people – especially experienced people – working on a project simultaneously means that your project will be finished more quickly. And because each step has been assigned to the best person for the job, you know that each phase of making your design a reality is being completed in the most efficient manner possible. In addition, multiple people working on a single project prevents boredom; energy and enthusiasm will remain high and your product will be finished and to market more quickly than if you worked on the project by yourself or with only one specialist. Read our comprehensive guide on bringing products to market.
  • Your ideas and designs will be treated with ultimate discretion. Signing a Non-Disclosure Agreement (NDA) is an industry standard for design and engineering teams. But you will also benefit from the accumulated knowledge that designers accrue after working on various projects in various industries for years. While we can’t always share our success stories publicly, we can adapt lessons learned from previous projects into a better solution for you.
  • Your product will be of higher quality. Why try to solve a problem multiple times when you can get it right the first time? An experienced mechanism design team has had multiple opportunities and projects that allowed them to experiment with a product similar to yours, which means that the testing has been done, the mistakes have been made, and now, instead of working to make your product right, you can work to make it better. This means you can work on reducing parts, finding parts with higher tolerances, and other things that will improve your mechanism design.
  • You’ll have a greater opportunity for Intellectual Property Ownership. Many mechanisms are rooted in fundamental mechanical concepts,
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3 Basic Steps of the Injection Molding Process

Injection molding is a popular manufacturing method for many reasons. It has proven especially valuable to those in the consumer product development sector, since plastics are a primary component of many consumer products, and injection molding is one of the best ways to manufacture plastics. Let’s take a quick look at the three major phases of the injection molding process, and then discuss the advantages and disadvantages of the process.

Injection Molding Process, Basic Step 1: Product Design

Design is one of the most important facets of the production process because it’s the earliest opportunity to prevent expensive mistakes later on. (Of course, determining whether you have a good idea in the first place is also important, but more on that here.) There are many objectives to design for:function, aesthetics, manufacturability, assembly, etc. The right design is one that accomplishes the required objectives to a satisfactory level, but it may take a lot of creativity to get there. Product design is most often accomplished with computer aided design (CAD) software, like SolidWorks. (Click herefor nine pro tips on how to best use SolidWorks in design and engineering.) Proficiency with CAD software is vital because it allows for quicker iterations and more accurate prototyping if necessary.

 

Some specific ways to avoid costly mistakes during the product design process are to plan for uniform wall thickness whenever possible, and to gradually transition from one thickness to another when changes in thickness are not avoidable. It is also important to avoid building stress into the design, such as corners that are 90 degrees or less. (Read more about Injection Molding Defects here.)

A skilled team of design engineers will be able to brainstorm, design, and improve upon a variety of solutions to meet the particular complexities of a specific project. The design team at Creative Mechanisms has combined decades of experience creating elegant solutions to complex problems. Meet some of our team here, here, or here, or visit our Customer Testimonials page to see what previous and current clients have to say about our product design capabilities. We think you’ll be impressed.

Injection Molding Process, Basic Step 2: Mold Design

After a looks-like, feels-like design has been tested and slated for further production, the mold (or die) needs to be designed for injection mold manufacturing. Molds are commonly made from these types of metals:

  • Hardened steel: Typically the most expensive material to use for a mold, and generally the longest-lasting (which can drive down price per unit). This makes hardened steel a good material choice for products where multiple hundreds of thousands are to be produced.
  • Prehardened steel: Does not last as many cycles as hardened steel, and is less expensive to create.
  • Aluminum: Most commonly used for single cavity “Prototype Tooling” when a relatively low number of parts are needed for testing. Once the injection molded parts from this tool are tested and approved, then a multi cavity steel production tool is produced. It is possible to get many thousands of parts from an aluminum tool but typically it is used for lower quantities.
  • Beryllium-Copper alloy: Typically used in areas of the mold that need fast heat removal or where shear heat is concentrated.

Just as with overall product design, mold design is another opportunity to prevent defects during the injection molding process. We have previously written blogs on the Top 10 Injection Molding Defectsand Avoiding Mistakes in Injection Molding, but here are some examples of how poor mold design can be a costly mistake:

  • Not designing the proper draft: This refers to the angle at which the finished product is ejected from the mold. An insufficient draft can lead to ejection problems, costing significant time and money.
  • Improperly placed or sized gates: Gates are the openings in a mold through which thermoset or thermoplastic material is injected. Each will leave a vestige (scar), which can create aesthetic or functional problems if not properly placed.

The number of parts (cycles) required, as well as the material they will be made of will help drive decision-making as to how and with what materials to create the mold.

Injection Molding Process, Basic Step 3: The Manufacturing Process

When a product has been properly designed, approved, and die cast, it’s time to start the actual manufacturing! Here are the basics of the injection molding process…

Thermoset or thermoplastic material in granular form is fed through a hopper into a heating barrel. (Learn more about the differences between plastics in our PLASTICS course.) The plastic is heated to a predetermined temperature and driven by a large screw through the gate(s) and into the mold. Once the mold is filled, the screw will remain in place to apply appropriate pressure for the duration of a predetermined cooling time. Upon reaching this point, the screw is withdrawn, the mold opened, and the part ejected. Gates will either shear off automatically or be manually removed. This cycle will repeat over and over, and can be used to create hundreds of thousands of parts in a relatively short amount of time.

injection molding process.png

photo courtesy of substech.com

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Mold Flow Analysis is Critical to the Consumer Product Development Process

old flow analysis is an often overlooked but important step in the injection molding process, and it’s absolutely critical to do whenever a large number of parts are going to be produced. Let’s learn more about this process, and how it can improve Return on Investment (ROI) for engineering companies, and simplify the consumer product development process. But first…

The basics of injection molding and why it’s a great manufacturing process:

Injection molding is a manufacturing process for producing parts in large volume. It is most typically used in mass-production processes where the same part is being created thousands or even millions of times in succession. Once the initial costs for design and tooling have been paid, the price per unit during injection molded manufacturing is extremely low. The price also tends to drop drastically as more parts are produced. Injection molding is most often used for parts made from various types of plastics. Visit our Plastics page, or take our PLASTICS course which are two of the most comprehensive resources available to learn about plastic characteristics, uses, and more.

Thermoset or thermoplastic material in granular form is fed through a hopper into a heating barrel. The plastic is heated to a predetermined temperature and driven by a large screw through the gate(s) and into the custom designed mold. Once the mold is filled, the screw will remain in place to apply appropriate pressure for the duration of a predetermined cooling time. When cooling is complete, the mold is opened, and the part ejected. Gates will either shear off automatically or be manually removed. This cycle will repeat over and over, and can be used to create hundreds of thousands of parts in a relatively short amount of time. Read our blog Avoiding Design and Engineering Mistakes in Injection Molding.

What is mold flow analysis?

Mold flow analysis is the process of simulating an injection molding cycle with a particular plastic and analyzing the results. Mold flow analysis should occur before the injection molding process ever begins, through the use of specialized software that simulates the design of the part to be manufactured. Since the flow of the liquid material in the mold makes a massive difference to the behavior of the product, this step can save a great deal of effort down the road. This software creates color maps of different properties of the design as they would be reflected in the actual mold flow. These may include heating/cooling, fill pattern, injection pressure, potential air traps, shear stress, fiber orientation, and many more properties. Mold flow analysis is a careful, hands-on-process meant for experts.

How does mold flow analysis improve the injection molding and manufacturing process?

The consumer product development process is much more complex than just creating a design and having a machine spit out material in a desired shape; plastics are not as inert as they seem and do not operate like static building blocks. The color maps created by mold flow analysis assist in adaptive changes of the design in order to create a quality product before the molding process actually occurs. This ensures that when a prototype or product goes into production, it is going to perform and behave optimally. Despite the overhead that it adds to the process, mold flow analysis more than makes up for this in terms of final quality. In fact, it has been considered a factor in keeping North American manufacturing competitive in the face of cheaper product development processes elsewhere. Furthermore, it demonstrates a commitment to quality, and is a good indicator of design and engineering firms who are competent, reliable, and produce quality solutions.

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