Design for Manufacturing (DFM) Report

January 24, 2012 acleveland No comments

As plastic product designs become more complex, Design for Manufacturing (DFM) plays an instrumental role in successfully launching new products on time and under budget.  Our DFM service allows customers to take advantage of the vast manufacturing experience and knowledge of the dedicated Quickparts manufacturing team.  This service (valued at $300) is offered free of charge to customers working with Quickparts on injection molding projects.  A comprehensive DFM report is available which includes process flow details, expectations for the build, and final DFM recommendations.

Quickparts is a business that has been providing custom-designed plastic and metal parts to product development companies since 2000. Many companies, from the multi-billion dollar operations to the two-man design shops, have utilized the benefits of using Quickparts.

You can find a sample report and learn more about Design for Manufacturing in the Learning Center at www.quickparts.com.

If you have any questions regarding this or any other injection molding information, please send us an email or give us a call at (770) 901-3200.

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Injection Mold Shut Off Angles

December 19, 2011 acleveland 1 comment

FREE Injection Mold SampleI hope the end of the year is treating you well. We have had a few conversations with customers recently regarding shut off angles, and I wanted to get one final post out to everyone this year to briefly discuss the subject.

A shut off angle is where two parts of the mold shut against each other to prevent plastic from passing through. This term applies where one part of the mold closes against another to form a slot or hole, or it is sometimes used to refer to the interface where a slide shuts against a core or cavity. Sometimes, the shutoff surfaces are parallel to the direction that the mold opens. When this happens, draft has to be added to avoid grinding the parts of the mold against each other. A 3 – 5 degree draft is ideal for these shutoff areas and will ensure the life of the mold. Without this amount of draft the mold will get damaged, and may potentially even “lock up” and not open. Even with hardened steel, lack of draft in this area will ruin the mold.

Understandably, many customers do not understand why we ask for this draft, but without it, every time the mold opens and closes, the steel will wear out in this area in a very short time. When this happens, repairs can be costly.

If you have any questions regarding this or any other injection molding information, please send us an email or give us a call at (770) 901-3200. Thanks, and Happy Holidays.

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:: Selecting The Right Injection Molding Material

November 29, 2011 acleveland No comments

Last month’s design tips discussed how draft angles are specific to each part that is built.  This month we will look at some standard injection mold resins and some of the properties that they possess.

When deciding which molding resin to use, one must consider the mechanical properties, molding properties, and cost of the resin selected for the given application.  Application-specific requirements will always drive the need for particular material properties, like tensile strength and elasticity.  Successful plastic part design is based on an understanding of processing related issues during manufacturing, such as mold filling, likelihood of flash, part ejection and the potential for warp and sink.  The table below lists some commonly used resins, along with brand names, and a high-level summary of their material properties and moldability characteristics.

Standard Injection Molding Resins

Please keep in mind that this is a concentrated view of how to select the right resin for your plastic part.  All major material representatives have application specialists that can help you with your selection.  We strongly urge you to discuss your project with one of these specialists prior to making your mold.

We hope this gives you some ideas for your next molding project.  If you have any questions regarding this or any other injection molding information, please send us an email or give us a call at (770) 901-3200.

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Draft is Your Friend…

October 25, 2011 acleveland 1 comment

Draft angles are needed so that a plastic part can be released from the mold without distortion or damage. The high pressures of injection molding force the plastic to touch all the surfaces of a mold’s cores and cavities. The cavity becomes so tightly packed that it is often difficult to remove the part. Sometimes, shrinkage will actually make it easier to take the part out of the mold, but in other cases, shrinkage will cause the part to stick to the mold’s cores. These natural occurrences call for draft angles.

No single draft angle is suitable for all parts. Each individual part requires a unique specification. Large parts call for more draft than small parts. Thin-walled parts that undergo high-pressure injection molding need more draft than parts that are subjected to lower-pressure molding. When calculating appropriate draft angles, the plastic material’s shrinkage and physical properties are also considerations. Sizeable draft angles and smooth polish should be used for parts molded in strong, stiff, abrasive, and gluey materials. Smaller draft angles can be utilized on soft, malleable, and slippery plastics.

From a cost and manufacturability viewpoint, the ideal draft angle is the largest angle that will not lessen the customer’s satisfaction with the product. The minimum allowable draft angle is harder to quantify. Plastic material suppliers and molders are the authority on what is the lowest acceptable draft.

I hope this gives you some ideas for your next molding project. If you have any questions regarding this or any other injection molding information, please feel free to contact me at (770) 901-3200.

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Choosing the Right Gate Type

September 27, 2011 acleveland 4 comments

Injection Molding SampleWe learned last month that selecting the optimal gate size and location is vital in the creation of any molded part. However, that is just half the story. Just as pivotal to the success of the design is the type of gate that is used.

There are actually four main types of gates that are frequently used when molding parts. Edge gates are often popular since they are fairly simple and cost effective, but may not always be the best choice. Here is a brief description of some gating options that will help you customize your design and really take your part to the next level.

Edge Gate • Suitable for medium and thick sections
• Used on multi-cavity two plate tools 
• Gate located on the parting line and the part fills from the side, top or bottom
• DOWNSIDE: leaves “vestige” at gate location which should be trimmed with a secondary process
Submarine Gate • Used in two-plate mold construction
• As parts and runners are ejected, the gate is sheared at the part
• Tunnel can be located either in the moving mold half or in the fixed half
• Sub-gate is often located into the side of an ejector pin on the non-visible side of the part when appearance is important
Sprue Gate • Recommended for single cavity molds or for parts requiring symmetrical filling
• Suitable for thick sections where holding pressure is more effective
• A short sprue is favored, enabling rapid mold filling and low-pressure losses.
• A cold slug well should be included opposite the gate.
• DOWNSIDE:  a gate mark is left on the part surface after the runner (or sprue) is trimmed off.

We hope this gives you some ideas for your next molding project. If you have any questions regarding this or any other injection molding information, please send us an email or give us a call at (770) 901-3200.

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Building Your Mold: Steel or Aluminum?

August 31, 2011 ewheeler 2 comments

“Out of which material should you build your mold, steel or aluminum?” This is a very common question that we receive from our injection molding customers and is an important decision to make. The answer is usually dictated by your project requirements, expectations, and what ultimately defines “success” for your project.

QC10 aluminum is an incredible product that machines quite easily (40% faster than those made out of P20 steel). This saves you time and money, with parts in hand in as little as 1-2 weeks. On the other hand, if we were to make a mold out of steel, it will typically run around 100,000 parts while maintaining a polished A2 finish on the cavities.

Will the parts look good if you buy an aluminum mold?

Absolutely, unless you are trying to obtain an optical grade finish, which would likely require a steel mold. Aluminum transfers heat almost 5 times greater than steel, and this gives us a large window for processing. Typically we can run 5,000 to 15,000 parts off an aluminum mold before resurfacing the part line.

So what kind of mold should you buy?

For low volume parts at a reasonable price with a fast lead time, aluminum is the way to go. If you need a few hundred thousand parts, or something that is optical grade, then we would suggest building your mold out of P20 or another grade of steel.

If you have any questions regarding this or any other injection molding information, you can email us at quote@quickparts.com or give us a call at (770) 901-3200.

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Avoiding Sink Marks

August 1, 2011 sestrada 1 comment

Let’s discuss one of the potential pitfall of designing for the process of injection molding. Melting plastic pellets and molding them into a part seems like a rather simple endeavor; however, it’s sometimes anything but. There are many factors to consider, and this month, we are going to talk about one of the more common: sink marks.

What is Sink?

 A sink mark is a local surface depression or void that typically occurs in moldings with thicker sections. They are also common in locations above ribs, bosses, or internal fillets. As the plastic cools at different rates in the mold, the surface hardens but leaves the thicker areas in the center still molten. As the thicker areas cool, they contract and leave depressions in the surface of the part; sometimes the part may even warp completely.

How to Avoid Sink?

  1. Core out the solid sections of your part to reduce thick areas.

    2.              * If you require the strength of a solid part, try using cross hatched rib patterns inside of the cored out area to increase strength and avoid sink marks

  2. As a rule of thumb,  make sure that all bosses and locating & support ribs are no more than 60% of the thickness of your nominal wall.

    3.  
      * Click here for a quide to recommend wall thickness by resin

Have any further questions about sink or enhancing your Injection Molding project?  Call your Sales Manager at 770-901-3200 to discuss your project today!

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The Ins and Outs of Electrical Discharge Machining (EDM)

June 29, 2011 sestrada No comments

When working with metal, whether it’s cutting a tool or machining a final part, some features are too small to produce using traditional machining methods. For these applications, a process called electrical discharge machining (EDM) is used. EDM is also referred to as spark machining, spark eroding, burning, die sinking or wire erosion.

What is EDM?

Electrical discharge machining (EDM) is a metal working process in which controlled sparking is used to erode away a work piece. The EDM system consists of an electrode and the part (work piece). Material is removed from the work piece by a series of rapidly recurring current discharges between the two electrodes, separated by a dielectric liquid and subjected to an electric voltage. It is one of the most accurate manufacturing processes available for creating complex or simple shapes and geometries within parts and assemblies.

When is EDM used?

EDM is primarily used for hard metals or those that would be very difficult to machine with traditional techniques. EDM typically works with materials that are electrically conductive and can cut intricate contours or cavities in pre-hardened steel without the need for heat treatment to soften and re-harden them. This process is most widely used by the mold making tool and die industries, but is becoming a more common method of producing prototype and production parts where quantities are relatively low. EDM manufacturing is a very desirable manufacturing process when low counts or high accuracy is required.

Some of the advantages of EDM include machining of:

  • Complex shapes that would otherwise be difficult to produce with conventional cutting tools
  • Extremely hard material to very close tolerances
  • Very small work pieces where conventional cutting tools may damage the part from excess cutting tool pressure
  • Delicate sections and weak materials – can be machined without any distortion since there is no direct contact between tool and work piece

Some of the disadvantages of EDM include:

  • The slow rate of material removal
  • The additional time and cost used for creating electrodes for ram/sinker EDM
  • Reproducing sharp corners on the work piece is difficult due to electrode wear
  • Specific power consumption is very high

Have questions about EDM and how it can help you?  Call your Sales Manager at 770-901-3200 to discuss your project today!

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The Art of Proto-duction

June 2, 2011 sestrada 1 comment

Injection molding is the manufacturing process that is responsible for producing most of the plastic parts that you and I come in contact with each day. While the process is capable of producing a vast range of designs, it can take some time and therefore does not lend itself well to changes down the line. It is for this reason that Quickparts has created a new injection molding concept called Proto-duction tooling.

What is Proto-duction Tooling all about?

We at Quickparts have perfected the process of building “Proto-duction” tooling, also known as “Prototype-to-Production” tooling. It uses production steel multi-cavity tooling, with the 1st cavity serving as the prototype tool. After the 1st cavity is constructed, sampled, adjusted, and approved, then the remaining cavities are built to match this prototype cavity. The result is a production multi-cavity, steel injection mold tool, created in half the time of the traditional 2-step process (building a stand-alone prototype tool, then a multi-cavity production tool).

What are the benefits?

One of the great benefits of proto-duction is that the construction timeline is reduced, since the typical ‘prototype’ tooling phase goes hand-in-hand with the construction of the production tool. Additionally, the overall tooling cost will also be reduced, since the stand-alone prototype tooling is avoided. Finally, it is important to note that financial risk is now reduced because you wouldn’t order the construction of the remaining production cavities until the prototype cavity is approved.

Proto-duction tooling is a cost effective way to produce prototype and production tooling. There are no geometry limits, no volume limits, and no manufacturing limits on your part. Any commercially available material can be used in the production of the part and any surface finish can be applied.

Please call a friendly Quickparts Sales Manager at 770-901-3200 to discuss your upcoming project and discover how Proto-duction tooling can benefit your design.

 

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Designing Parts for Lettering & Logos

May 12, 2011 phunter 3 comments

A common design feature seen in injection molded parts is the use of lettering and logos. Designers use this feature for many reasons; to illustrate a brand identity, convey important end user instructions, aid in assembly, or display a part number or legal warning. The injection molding process allows lettering and other surface decorations to be easily incorporated into plastic parts. Once the lettering has been incorporated into the mold, each part will display the feature with few or no extra steps. This can save a significant amount of money by eliminating the expense of adhesive or painted labels.

Recessed vs Standoff Lettering & Logos

When applying lettering or logos to a mold, you will need to indicate whether you want your lettering to appear as recessed into the part or raised off of the part (also known as stand-off). This decision determines how your mold will need to be cut. For economic reasons, lettering is generally engraved into the mold which appears as raised letters on the parts. This enables the mold to be polished which provides a better finish on the surface of the parts. Engraving into the mold also extends the life of the mold since you do not have raised small features that wear faster than others. 

The Rules of Lettering & Logos

Engraved lettering or logos in the mold, if not done properly, can cause imperfections in the final part such as streaks, tear drops or flow marks around the features. These defects are usually caused by improper material flow into the letters. The following rules will help you to avoid these problems in your molded parts:

Rule of Thumb #1: Apply a radius to all sharp corners of the lettering. Deep, sharp lettering can lead to defects from air trapping in the mold.

Rule of Thumb #2: Limit the depth or height of lettering into or out of the part surface to approximately 0.010”. Letters and logos raised higher than 0.010” are unnecessary as they seldom wear out during the life of the part.

Rule of Thumb #3: Don’t forget to draft your features. The letter or logo sidewalls should have a draft angle of at least 3o to ensure proper fill.

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