The majority of the delay in developing the moulds is not due to slow manufacturing, but rather to avoidable errors in the tooling decision making. Even when errors in the development of the mold are detected late, fixing them will virtually prolong the product release schedule.
Most of OEM teams continue to assume that after giving them the files, it is the factory that should simply get it to work in a short time. As a matter of fact, most severe schedule slippage occurs months ago, when the design is being finalized, communicating with suppliers, and making decisions. These initial omissions multiply on a stage: design of the molds, machining, sampling, validation, and finally preparation of mass production. Knowledge of the most common error in mold development will enable product managers, engineers and sourcing teams to take proactive measures instead of responding to the problem once the program is already in the flames.
Why Mold Development Mistakes Translate Directly Into Launch Delays
The discovery of the problem of molds is untimely and unproportional in costs due to the inability to solve them.
Adjustments in the tooling following the initial trial (T1 ) are usually by re-machining, replacement of electrodes, or even re-cutting complete cavity /core inserts. The adjustment cycle may take 26 weeks with parts of varying complexities and shop load. The corroborating effects of these corrections are that new samples need to be made, they need to be re-validated to specs, they need to be re-tested to fit/function, and in some cases they need to be re-submitted to regulatory authorities. It can take months to complete final production tooling approval what started as what appears to be a minor geometry adjustment.
The major distinction is the timing. A design change to be incorporated prior to cutting of mold steel may be absorbed within days or one week. This post T1 change is normally followed by a complete rework cycle. That is why, even seasoned program managers do not consider the development of mold as a production hand-off, but one of the important decision gates in the entire hardware development process.
For a deeper look at the complete process, see our guide to injection mold development.
Mistake #1 — Incomplete or Ambiguous CAD Preparation
Unfinished CAD information is one of the solitary biggest causes of early delay in mold programs.
Most teams present models that seemingly look complete; however, they lack much important manufacturing data: draft angles, equal wall thickness, correct fillet/radius intersections, or tolerances being explicitly described. This then causes suppliers to make assumptions. When later the assumptions prove false, the mold should be fixed, in practice once steel has been cut and initial shots lead to the discovery of the issue.
The most common CAD triggers and the effect they have on delay are as follows:
| CAD Issue | Resulting Delay |
| Missing draft angles | Rework after T1 |
| Inconsistent wall thickness | Warpage correction cycles |
| Undefined tolerances | Measurement disputes |
| Surface ambiguity | Polishing and cosmetic rework |
Early mitigation of these problems presents risk reduction that is dramatic. Get tips that apply in the field more in our common CAD issues in mold development.
Mistake #2 — Underestimating Mold Design Impact on Assembly
The independent decisions made on tooling geometry often cause headaches on downstream assembly.
The location of mold parting lines, gate positions, ejector pin position, and draft arrows can affect both the fit of parts with each other, the way they are arranged in a package, and the ease with which they can be fitted with other compatible parts. Unless such factors are checked in the light of a complete assembly, it is not uncommon to find interference, stack-up tolerance issues or cosmetic damage in a team only after molded parts have been received, and at times, even pilot builds.
The later such problems are brought up, the higher and more time-consuming are the costs and efforts to fix them. Many of these surprises can be avoided by proactive mold design reviews which also incorporate assembly simulation or fit-check samples.
Read more about this critical relationship in mold design impact on assembly.
Mistake #3 — Treating Quality Issues as Production Problems
A very high ratio of what teams refer to as quality issues in the production process are restrictions inherent in the very mold.
Teams may use weeks of effort to obtain injection parameters, cycle-time control, or material adjustment to eliminate flash, short shots, sink marks, or dimensional variation only to find in retrospect that the cause of the problem was poor temperature distribution in mold steel, venting, and cooling layout, or gate design that was not capable of producing the intended consistency.
The development of quality capability is much defined in the process of mold development. Efforts to offset the tooling constraints by process control are not efficient and are seldom sustainable. The sooner the team can transfer the focus away offix the process to fix the tool, the sooner the program will recover.
Explore this topic further in mold quality vs mass production consistency.
Mistake #4 — Skipping or Rushing DFM Review
Design for Manufacturability (DFM) has often been considered as a hastily undertaken formality and not as a decision gateway.
An extensive DFM process requires premature trade-offs: cosmetic surfaces vs. cycle time, tight tolerances vs. tooling cost, location of gates vs. knit-line strength. The trade-offs are postponed when DFM is hastened or omitted in the name of saving time, and nearly always reoccur as costly rework at trial, or as production start-up.
The most effective programs consider DFM as a formal gate having documented approvals and clear ownership.
See practical examples of how proper DFM prevents rework in how DFM reduces mold rework.
Mistake #5 — Expecting Mold Development to Self-Correct
Molds do not stabilize themselves.
Other teams follow a reactive approach: make trials, see the problems, modify the parameters, repeat, hoping that the problems will fade with time. Practically, this method tends to extend the process of validation and risk to finding new problems at an advanced stage.
Formal validation strategy with well-defined success criterion, responsibility of every issue, and disciplined decision making at every trial will be needed to keep programs within control.
How OEM Teams Can Prevent Mold Development Delays
The encouraging fact: the majority of the delays mentioned above can be avoided by disciplined front-loading of decisions.
The following is a checklist which is practical and used by experienced program managers to minimize risk:
| Prevention Area | Preventive Action |
| CAD readiness | Freeze geometry and tolerances |
| Design validation | Allocate sufficient DFM time |
| Decision ownership | Define clear approval authority |
| Trial planning | Expect and plan for iteration |
| Communication | Document all assumptions |
This method when adhered to converts most of the corrections to the low-cost, pre-steel stage.
Conclusion — Most Mold Development Delays Are Preventable
The speed of the tooling can hardly cause the delay in the product launch, but the unresolved decisions reemerging late in the development of the mold can.
Teams that are on time, are not always working with faster mold makers, it is those who are making disciplined, well documented decisions early, own them, and mold development is more of an engineered process, than a production hand-off.
The trend, over two decades of handling hardware programs in various industries, is exactly the same: spend time in the beginning being clear, validating and making trade-off choices, and you will save just about as much time at the end.