80 Questions Moldmakers Should Ask Themselves … and ...

As a consultant, I continually see mold and molding issues that could easily have been avoided. The most common problem has little to do with cutting steel. The problem is failing to consider, obtain and verify all the pertinent information up front&#;prior to the mold&#;s construction.

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It&#;s the responsibility of the moldmaker to ensure the mold will produce dimensionally, functionally, and aesthetically acceptable parts for the life of the program. There is no way to achieve that goal without first determining what the dimensions, function, aesthetics, and lifespan requirements are from the customer.

Most clients are not well versed in our industry, but all too often think they are experts. Still, they prefer to work with knowledgeable vendors&#;someone who is looking out for their best interest. It is the moldmaker&#;s responsibility to educate the customer, which also serves to protect the moldmaker. For example, no matter how insistent a customer may be, the moldmaker should never agree to build a seven-cavity hot-runner family mold for parts of various sizes and wall thicknesses in a high-shrink semi-crystalline material.

Don&#;t laugh. This is a real example, and the project is 11 months late and will soon be converted into four molds. The expensive hot-runner system is now a boat anchor. If that wasn&#;t bad enough, the moldmaker agreed to amortize the mold into the piece price, with no down payment. Ultimately, if the molder can&#;t produce acceptable parts, the finger is going to get pointed at the moldmaker.

This tooling checklist is focused on communicating all the pertinent information about the mold from and to the customer.

With all this in mind, I compiled a list of questions that should be asked both internally and to the customer to help avoid any delays or oversights that could affect getting paid for the current mold, as well as any future tooling orders. I am not going to expand on why each question should be asked. If you are an experienced moldmaker, you already know why. None of the questions below are about the details of the mold design, such as the type of interlocks, plate thicknesses, eyebolt holes, etc. The list is focused on communicating all the pertinent information from and to the customer.

If the molder can&#;t produce acceptable parts, the finger is going to get pointed at the moldmaker.

Initial Inquiry Questions

 1.  How did you hear about us?

 2.  What is the end use of the product (medical, automotive, consumer, etc.)?

 3.  Are there any mating parts?

 4.  Do you need any part-design assistance?

 5.  What are the expected annual production quantities?

 6.  What is the expected lifespan of the product?

 7.  Do you have a CAD file of the part? If so, what is the file format?

 8.  Do you have or need a 3D-printed or machined prototype?

 9.  Do you have a 2D dimensioned drawing of the part?

 10.  What is the material type?

 11.  Will the parts be made in more than one type of material or more than one color?

 12.  Do you have any mold-design specifications that need to be adhered to?

 13.  Can we get your molder involved in future discussions?

 14.  Is the number of cavities desired based on the mold cost, part cost, or production requirements?

 15.  If the mold is to be a MUD or other quick-change insert type, is a specific frame size required? If yes, what is the frame size or number?

 16.  Do you know if you want a cold runner, hot bushing, hot runner, valve gate, etc.?

 17.  Are there any interchangeability requirements, such as various versions of the part or engravings?

 18.  Are there any inserts that will be overmolded?

 19.  Are there any secondary operations that might affect the mold design?

 20.  What are the surface finish requirements for the cavity?

 21.  What are the surface finish requirements for the core?

 22.  How many samples will you need initially?

 23.  Are any inspection or testing criteria required for the parts?

 24,  Are there any mold qualification requirements?

 25.  Is there anything else we should know?

 26.  How many other moldmakers are quoting this project?

 27.  Are any of these moldmakers offshore?

 28.  When are you expecting to place the order for the mold?

 29.  How critical is the delivery date?

 30.  If you gave the potential client a ballpark mold cost, what was their reaction?

Internal Review of the Supplied 3D Model

 31.  Did the model translate well?

 32.  Should the part design be modified to reduce the mold cost or increase its longevity?

 33.  Can the model be modified in-house?

 34.  Are any actions required (cams, lifters, two-stage ejection, unscrewing, etc.)?

 35.  Are there any holes or features requiring shutoffs?

 36.  Does the part have uniform wall thickness?

 37.  Is additional coring needed?

 38.  Is there sufficient draft to prevent sticking or scuffing in the cavity?

 39.  Is there sufficient draft to prevent sticking or scuffing on the core?

 40.  Are there any undercuts?

 41.  Are there radii on both internal and external corners?

 42.  Should any radii be removed to eliminate cavity impression in both halves of the mold?

 43.  Are there any ejection concerns?

 44.  Are there any gating concerns?

 45.  Are there any filling concerns?

 46.  Should a flow analysis be considered?

 47.  Are there any cooling concerns?

 48.  Should high-conductivity materials, or conformal cooling be considered?
 

Internal Review of the Supplied 2D Drawing

 49.  Does the 2D drawing have everything defined? Everything includes

        a.  Dimensions, 

        b.  Tolerances,

        c.   GD&T requirements (straightness, flatness, concentricity, etc.),

        d.   Surface finish or texture,

        e.   Notes.

 50.  What is the date and revision level of the drawing?

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 51.  Are the critical dimensions identified and toleranced?

 52.  Are there any dimensions or tolerances that are not obtainable for tooling or molding?

 53.  Has the material type and grade been specified?

 54.  Does the material contain any abrasive fillers, such as glass?

 55.  Does the material contain any flame retardants or other additives?

 56.  Do any of the notes refer to documents that were not provided?

 57.  Should a prototype tool be considered?

The more steps we take up front to minimize risks, through the collaboration of the concerned parties, the more competitive and profitable we will be.

Part Design Review with Customer&#;Prior to Mold Design

(In addition to any concerns or questions from above.)

 58.  What is the controlling document&#;a 3D model or a 2D drawing?

 59.  Are you familiar with the inherent issues of family molds?

 60.  Are runner shutoffs required?

 61.  Is the intended gate location acceptable?

 62.  Can a gate recess be added?

 63.  Can ejector-pin bosses be added on deep ribs?

 64.  Are samples and 2D drawings of the mating parts available?

 65.  Are alternate material types or grades acceptable?

 66.  Are you familiar with anisotropic shrinkage?

 67.  Who is specifying the shrinkage factor?

 68.  Who is supplying the material and colorant?

 69.  Are the intended molding machine&#;s specifications available?

 70.  Is the molder planning on using a robot or picker?

 71.  Is it acceptable if the engraving is raised on the part?

 72.  Is a recycle symbol, date clock, revision symbol, or cycle counter desirable?

 73.  Do you have artwork for any engraving?

 74.  Are the font type and size specified?

Mold-Design Review with Customer

(In addition to any concerns or questions from above.)

 75.  Is the cavity number location, size, and depth acceptable?

 76.  Are the ejector pin locations acceptable?

 77.  Are the witness lines from any actions acceptable?

 78.  Should some areas be left steel safe and adjusted after sampling?

 79.  Should any spare parts be made?
 

Molding Considerations

If you think molding issues have no effect on the part or mold design, think again. For example, sink and knit lines will affect the gate location. Splay and jetting will affect the gate type, size and location. Flash will affect shutoff considerations, steel types and heat treatment. Sink, warpage, and material type will affect both the part and mold design. Burn marks and shorts will affect the vent types and locations. Color values will affect the part&#;s wall thickness and mold&#;s surface finish.

 80.  What are the limitations on each of the following?

        &#;  Color (L, a, b, Delta E, gloss),
        &#;  Gate vestige,
        &#;  Sink,
        &#;  Warp,
        &#;  Knit or flow lines,
        &#;  Flash,
        &#;  Shorts,
        &#;  Splay,
        &#;  Burn marks,
        &#;  Black specks,
        &#;  Grease or dirt,
        &#;  Other.

 

Our business is full of risks. The more steps we take up front to minimize these risks through the collaboration of the concerned parties, the more competitive and profitable we will be.
 

Injection molding is a versatile and precise process, making it ideal for OEMs that rely on complex, highly engineered plastic parts for high-performance applications such as medical devices or automotive engine components.

Given the importance of these injection-molded parts &#; and the potential far-reaching impact of part defect or failure &#; selecting a custom injection molding partner must be a carefully considered decision. As a result, OEMs must ask the right questions to gain insights and assurances to help them make the best strategic choice.

Often, these questions revolve around project-related design, materials, process optimization, quality assurance, testing, etc., and the injection molder&#;s engineers are usually best suited to answer.

As the trusted custom injection molder for OEMs in a range of industries, Kaysun engineering professionals routinely field the frequently asked questions we&#;ve compiled and answered here.

1. Which plastic should I use for my application?

Material selection is uniquely application-driven since characteristics and factors such as mechanical properties, performance requirements, tooling needs, operating environment, regulatory standards, and price all come into play. Approving a tentative plastic or suggesting a &#;good fit&#; based solely on specs and a print would be a disservice to manufacturers and the injection-molded parts. Kaysun is committed to being an injection molding partner that comes alongside OEMs to guide discussions and choices to match design, materials, and goals.

2. Can I substitute plastics?

There are often opportunities to substitute materials for various reasons, but it&#;s typically not a simple swap-out. Mechanical properties, thermal performance, chemical compatibility, aesthetics, potential tooling changes, processing differences (cycle times, weight, etc.), dimensional stability, secondary operations, compliance considerations, and cost may all be impacted. The expertise of an injection molder is critical in weighing advantages and disadvantages before deciding. Kaysun&#;s specially trained engineers and our 10 master molders offer analysis on plastics behaviors, mold flow, and potential barriers to success that may not otherwise be readily apparent.

3. Should tooling be made from aluminum or steel?

Steel tooling was once an expensive and time-consuming option that made the comparative speed and cost-effectiveness of creating aluminum tooling an attractive alternative in certain situations. Over the years, manufacturing advancements made cutting steel as efficient as machining aluminum, and steel quickly became the tooling material of choice. Steel provides the closest match to actual production conditions during tooling design and testing, along with better structural integrity and consistent molding repeatability to ensure tight tolerances and complex geometries are maintained to top-quality standards.

The choice really isn&#;t either/or. Selecting the proper grade of molding tool steel is essential to achieve the desired project outcomes. It influences how plastics behave during molding, which could impact cycle times, part criteria, production volume, and overall cost and maintenance.

4. Can tooling design be modified after the build is complete?

Technically, tooling design can be changed at any point in production. However, where the tooling change falls in the process can be both challenging and costly. Depending on the scope of the changes and status of qualification, Kaysun may be able to offer in-house adjustments to existing tooling to mitigate outsourcing expenses and minimize downtime while accomplishing the goal.

5. Who owns the part design? Tooling?

Ownership typically depends on the arrangement agreed to between the injection molder and customer. Kaysun has non-disclosure agreements in place with all customers to protect intellectual property. Proprietary information and processes, part design, and tooling are and remain the property of the OEM.

6. What experience do your engineers have with scientific molding, DfM, and mold fill analysis?

Kaysun engineers have extensive training and proven experience in scientific molding, Design for Manufacturability (DfM), and mold fill analysis. Expertly applying these predictive principles and processes translate to more efficient injection molding.

DfM focuses on part design optimization and defect prevention through examining part geometry, wall thickness, draft angles, and material flow early in the design process. Should challenges arise they can be corrected at the point of least time and monetary impact. Likewise, affirming that a design is manufacturable early on prevents costly redesigns and delays.

Simulation tools such as mold fill analysis provide valuable insights into the behavior of materials during injection molding. They help engineers visualize how plastic flows through tooling, finding potential defects such as sink marks, and making adjustments to optimize the design before tooling is made. Kaysun engineers depend on mold fill analysis and other advanced simulation software to refine part designs and molding processes &#; resulting in lower development time and costs without compromising quality outcomes.

7. Do you offer value-added services?

Molders that offer value-added services (aka, secondary operations) play an important role in supply chain management and delivering cost efficiencies for OEMs in need of welding, heat staking, machining, assembly, etc. Kaysun's vertically integrated services are customized to specific project needs, and provide competitive advantages in consistent product quality, timely production, limited risk exposure, and enhanced reliability.

8. How is automation incorporated into your molding process?

Automation is increasingly important in injection molding to improve efficiency, consistency, and safety. At Kaysun, we use a variety of automated systems, and nearly all of our machines include robotics for part removal, insert loading, and secondary operations such as assembly or inspection. Automation allows us to maintain consistent cycle times and cooling times, manage quality, and improve overall throughput, which is especially beneficial for high-volume production runs.

9. How old are your presses? What does maintenance and replacement look like?

Presses are the workhorses of injection molding. How a molder invests in and maintains presses could signal their approach to leaning into challenging projects and innovative solutions. Annually, Kaysun replaces two or three molding machines that are nearing the end of their operational life, and also adds two or three new machines to increase capacity. This regular best practice helps prevent equipment-related downtime and also ensures production is supported by a fleet of state-of-the-art machinery and technologies.

10. What process controls are in place for quality assurance?

The precision and reliability required of complex applications means injection molding quality control held to the same exacting standards. Kaysun is committed to cross-functional, collaborative teamwork and implementation of rigorous quality control. In-process monitoring using RJG technology, dimensional inspections, and in-depth statistical analysis of tight tolerances is supported by our in-house Quality Lab. Quality technicians conduct comprehensive testing on samples at intervals of 3 times per shift to ensure all parts conform to specifications.

11. How do you manage part defects and nonconformities?

Automated inspections using RJG technology continuously scan for defects. Should a suspect cycle arise, robots extract the nonconforming parts for further engineering evaluation and correction. Should dimensional nonconformity occur, engineers backtrack to the last known good inspection to analyze data from that point forward to find and correct errant dimensions that caused departure from specifications.

12. What sustainability initiatives have you implemented to reduce your corporate carbon footprint?

Creating a more sustainable workplace can be challenging for manufacturers, but Kaysun is up to the challenge. With the support of our internal Green Team, we have several initiatives that focus on reducing our carbon footprint.

Since injection molding consumes a lot of energy, finding ways to conserve it is a primary goal. Installing our Central Material Handling System saves 1.5 million kilowatt hours per year. We also committed to plastic-waste-to-energy conversion in partnership with renewable fuel and power producer Convergen Energy , diverting more than 2.7 million pounds of plastic waste from landfills and helping our local utility company reduce greenhouse gas emissions by 40%.

LED lighting, installation of a more efficient tool chiller system, and other facility upgrades also contribute to helping Kaysun be responsible stewards &#; a goal recently recognized by receiving a Focus on Energy Energy Efficiency Excellence Award and a grant to fund future conservation efforts.

Understanding the intricacies of injection molding is essential for any manufacturer looking to partner with an injection molder that can consistently produce high-quality plastic parts. By addressing these frequently asked questions, we hope you gained valuable insights into how Kaysun can help you achieve your injection molding goals.

Have more questions? Great! Reach out to the Kaysun team any time. We&#;re here and happy to help.

If you have more questions or would like to discuss your project in detail, feel free to reach out to our team of experts. We&#;re here to help you succeed!

Contact us to discuss your requirements of custom mold plastic. Our experienced sales team can help you identify the options that best suit your needs.