Tooling Management for Plastic Injection Molds in China

What are the best practices for tooling management (specifically for plastic injection molds) in China?

Closely following up on the design & fabrication of molds for your plastic injection molded products is often necessary for a number of reasons:

  • It is often a significant investment, and it is not always easy & cheap to fix;
  • Delays at this stage will certainly cause delays for your entire project;
  • Good tooling that is properly validated goes a long way toward good quality production.

In this post, we’ll outline some of the key risks you face when manufacturing and managing your tooling for plastic injection molds.

 

Key risks faced when manufacturing and managing tooling

In most cases, the main sequence of actions, and the corresponding risks you face and need to mitigate or avoid, are as follows:

ActionTypical risksHow Sofeast helps
A mechanical engineer works on detailed 2D and 3D drawings of plastic partsThe choice of material & finishing, as well as the geometry of the parts, may lead to issues in the productionConduct a Design For Manufacturing (DFM) review; warn of potential issues and suggest changes if needed
The part drawings are sent to potential suppliers for quotationsInsufficient specifications (e.g. how many shots, tolerances…), and potential leakage of valuable intellectual propertyProbing until there are sufficient specifications; quotation requests to proven suppliers that have signed an NDA/NNN agreement
Quotations & lead times are compared for screening uncompetitive suppliers offMisunderstandings, such as unrealistic lead times (since tooling always has to be modified)A written agreement that spells out key clauses (IP ownership, return of tooling…) and is enforceable
Visit of the top 1 or 2 potential suppliers for final selectionBuyers pay excessive attention to ease of communication, to automation, etc.One of our engineers can conduct a process audit that highlights the risks for your production
Mold 3D designThat design is considered proprietary by the mold fabricatorMake it clear that the buyer must get that drawing’s final version
Tooling fabrication Delays in case of larger projects’ tooling being made at the same timeTypically no involvement, or visits to “push” gently if needed
T1 (first articles off tooling, trial 1)Issues are noticed but are not addressed well, leading to too many rounds of fixesInspection of first articles, clarification about their cause, planning for proper fixing
Following trials (T2, T3…) after corrections of toolingDelays in case of larger projects’ tooling being made at the same timeScheduling of inspections to “push” gently if needed; inspection on-site or in our office
Transfer of mold(s) to the plastic injection molding factory, if not the same companyThe molding factory may not sign off on a mold formally and later complain about it as the cause of quality issues (a big risk if different countries)Management of the formal acceptance process and documentation of setup parameters
Setup for first mass production of plastic partsNon-respect of the same settings as those in the latest trialWe can help document the settings and check them (and other topics) during the setup
During mass productionComplications due to variations of temperature & humidity; unauthorized use of regrind materialRegular inspections during large production runs, with tests on the parts’ physical properties (among others)
Tooling is kept off the pressTooling may not be maintained; in extreme cases, it may be used to make parts without your authorizationWe can pull the tooling out of the factory between batches and store it in good conditions in our facility
You decide to switch to another supplier, and you pull the tooling from your current supplierThe current supplier may resist; the new supplier may not sign off on a mold formally and later complain about it as the cause of quality issuesWe help you check the tooling carefully (a.k.a. ‘tear down’) and we guide you through the right process for the transfer.
Replacement of the mold after its useful lifeRe-use of the same mold design without much thinkingWe review past issues and suggest lessons learned and necessary changes. And, if volumes went up, changes such as more cavities might be worth the extra investment.

We hope this table gave you a good overview of the major risks you need to look out for. We can intervene at every stage, but it only makes sense for expensive molds that are then used in very large productions.

 

Services related to sourcing and managing tooling that Sofeast provides

Let’s cover a few of the services related to tooling management for plastic injection molds that we perform most often:

 

Design for Manufacturing Review

Certain part designs cannot be injection-molded. Some designs can be made this way, but they are likely to lead to a number of issues, including difficulty to eject the parts, poor aesthetics, high need for manual rework, and so on.

Changing the design so that it makes good manufacturing easy is usually 10 to 100 times faster and cheaper than reworking a batch of products and making corrections on a mold.

How Sofeast can help…

We can do a DFM review on the plastic part drawings, and if necessary also on the tooling’s design. It usually takes about 5 to 10 hours (to be confirmed based on complexity), at 45 USD per hour.

 

Picking the Right Supplier

Identifying a reliable manufacturer for your plastic parts and your molds is as critical as finding a great supplier for finished products. (In many projects, it does not matter whether tooling fabrication is done by the injection molding factory or subcontracted to a specialized tooling shop, as long as the right expectations are laid out and accepted. In some other projects it matters a lot.)

How Sofeast can help…

One of our project managers who are familiar with tooling management can contact plastic suppliers that are a good fit for the size of the parts, the type of polymer to use, the tolerances on dimensions, etc. We include some tried-and-tested suppliers in that study. And we collect quotations.

We described how we identify factories to supply tooling (or other things) on this page, and the cost is 38 USD per hour. We also help set the right expectations from the start with the supplier about IP ownership, the ability to pull the molds at any time, and other important topics.

 

Tool Qualification During Fabrication

Steel hardness reports

Hard steel material is more expensive to purchase and harder to machine. There is a temptation for suppliers to quote a certain grade of steel, say H13, and actually use a softer material that will be useful for fewer shots.

(It does not happen often. You, as the buyer, are at higher risk if the tooling fabrication shop is unknown and if they assume injection molding will be done far away from them. But in some projects it is a real risk.)

How Sofeast can help…

We usually test steel hardness by using the tool fabrication shop’s testing equipment.

 

Close up tooling examination

You may want the assurance that your tooling is provided with the correct parts, spares, etc. and if all the elements function correctly. The objective is to avoid having to send molds back to the fabrication shop for fixes after the final signoff. Those fixes can be quite expensive and are sometimes poorly done, requiring another round of fixes.

How Sofeast can help…

We have engineers on our staff with deep experience in tool making and injection molding who will perform the examination and report back their findings and recommendations.
We typically look at 50+ points to confirm, for example: Spare parts/inserts included per P.O., Cooling circuit circulation tested with air, or Are all heaters and nozzles heating well?

Such an examination starts from 500 USD in South China or Vietnam, and costs vary for other locations.

 

Tool Qualification at End of Fabrication

The most basic approach to confirm a mold is acceptable is to check the first shots coming out of it — typically about 5 to 10 parts to be inspected very closely. There is virtually always the need to do another trial, but very clear feedback has to be given to the fabrication technicians. The toolmaker should do this, but for extra peace of mind, we can also send an engineer to oversee their testing and provide feedback to assure the tooling is ready to be used in mass production.

How Sofeast can help…

Mold capability validation supervision

This is quite an in-depth check on the finished tooling before it leaves the toolmaker’s facility. When they’re testing it our engineer does the following:

  • Checks the mold based on our standard checklist
  • Records the setup parameters (time, pressure, temperature…)
  • Records how many shots are necessary before the parts off the mold are good
  • Records the information on the machine
  • Records the effective cycle time
  • Checks if the factory checks the parts periodically (every 1 hour), especially for CTQ points
  • Checks whether the factory records their QC findings and use them to calculate the Cpk index
  • Checks if there are quality issues on the parts that are made

Mold Capability Validation Supervision (in China) provides the maximum assurance that tooling will not reach your or your supplier’s factory from the toolmaker unless it’s working completely as you expect.

First article inspection

We often do a First Article Inspection (FAI) on the first parts out of tooling. We go to the factory and check the following points:

  • Part structure
  • Visual aspect (looking for common defects)
  • How the runner separated from the part
  • Dimension check
  • Assembly test, if needed

In case of issues, we try and give visual explanations to the supplier so there is little room for misunderstanding.

Other clients simply ask us to receive the first-off samples and inspect them in our facility.

 

Before/During Plastic Injection Molding

Technical process audit

For large-scale productions and/or cases where quality absolutely has to be consistent, you need to be sure that your injection molding manufacturer has mature systems & processes.

How Sofeast can help…

We have auditors who are experts in plastic injection molding and can audit and assess your supplier’s technical ability and in-house processes on-site by performing a Technical Process Audit (TPA).
They will report back to you on numerous points, such as: Production Capacity, Technical Capability, Process Controls, Preventative Maintenance and its Effectiveness, Tool/Die Storage, General Housekeeping, and many more.

A TPA starts from 650 USD in South China or Vietnam, and costs vary for other locations.

Here’s an example of a real TPA we performed on plastic injection molding tooling:

plastic injection mold technical process audit sample report

Product Inspections on the finished parts/products

This is a very standard and very common service that aims at confirming quality and quantity before the parts or products are shipped out of the injection molding factory. You want to keep the costs of fixing issues at the factory, rather than having to manage that on your side.

How Sofeast can help…

Our QA technicians go to the factory, pick a representative set of samples based on the ISO 2859-1 standard, and carry out a visual & dimensional inspection. Other on-site tests are performed as needed – for example, burning a part to confirm the type of polymer used, or testing physical properties as a way to detect if too much regrind material was used.

The cost for a product inspection involving 1 technician for 1 day is 299 USD in most manufacturing areas in China, Vietnam, and India.

 

After production has finished

Tooling Custody & Management

Leaving your tooling with your Asian plastic injection molding supplier is risky. They might use it to manufacture your parts or products without your permission or store it insecurely leading to damage.

How Sofeast can help…

We help you by storing your tooling safely in our Chinese warehouse. We pick it up or receive it after a production run (noting what condition the tooling is in), store it securely, and then return it back to your supplier before the next one.
This maintains its condition, reduces the risk of IP theft, and allows you to switch suppliers without extra stress of negotiating the release of your expensive tooling from your old supplier (who may be tempted to hold onto it if they know they’re losing your business). Learn more about our tooling custody and management service.

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Do you have any other questions about tooling management for plastic injection molds? We’re here to help. Contact us or leave a comment.


 

P.S.

Listen to this episode of our podcast

7 Common Plastic Injection Mold Tooling Development, Approval, & Maintenance Pitfalls

Read even more about plastic injection molding and tooling management

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