Moldmaking Resource Plastic Mold Makers, Mold Designers, Mold Repair Guide The mold components in a plastic injection mold play a very important role in any plastic injection mold, plus they can become a considerable expense. For these reasons it is important to find the way to get the best components for the best price.
Because we are creatures of habit, and some shops are very reluctant to change from the “way we have always done it”, it sometimes is difficult to convince the decision makers to try anything new.
In today’s highly competitive market, every dollar saved is very much a dollar earned, so it makes sense to at least have an open mind.
The Not-Invented-Here syndrome
On one end of the spectrum are those shops who make everything, or at least most things themselves. This might make perfect sense if it is not possible to find the quality or speed of delivery required, or if there is some proprietary knowledge that needs protecting.
This approach may also be just plain stupid. A simple example is that of the mold base. Most companies how buy machined mold bases from reputable companies that specialize in custom mold base manufacturing.
If the average mold making shop tried to compete with the price and delivery of these companies they would quickly lose money. Some shops obviously do very well making their own mold bases, but unless you have the skilled help and CNC machine tools to do the job quickly and accurately it only makes sense to outsource the job.
Typical mold components
Mold bases
Ejector pins
Core pins
Slide assemblies
Lifter assemblies
Hot runner systems
Date clocks and wheels
Parting line interlocks
Wear plates
Gate inserts
Hydraulic slides
Unscrewing mechanisms
Collapsible cores
Roller pullers
There are many other mold components that are used in a typical injection mold. Nearly all of them can be purchased ready to be custom fitted for your individual job.
Things to look for in quality components
Customer service is critical. Cultivate a good working relationship with the suppliers and they will hopefully reward you with excellent service. Mold making is fraught with crises and emergencies, and a good supplier will be there to help in the event of a problem.
Consistency in quality. Good components are held to the tolerance indicated, every time. A good example of this is the Dayton Pin company or System 3R. With both companies I have seen out of tolerance parts just once each over the span of decades. On the other hand, some suppliers regularly ship low quality parts and probably the only reason anyone buys from them is because they are the only game in town.
Another benefit is that you don’t have to pay for scrapped parts, at least not directly. If you have ordered a custom core pin that is difficult to grind, for example, and the grinder scraps the first two attempts, you only have to pay for the finished product.
Prompt delivery means everything. Just-in-time delivery is the norm, sometimes a single day can mean disaster for a company. I have seen a project manager catch the first parts out of the press, run out the door and race to the airport; just to get the parts out on time. If the mold component delivery had been late, the job and customer would have been lost.
Innovation. Competition is fierce among suppliers and innovative companies are constantly finding new and improved ways of doing things. Consider the parting line locks of the past compared with those in use today. Few people use the old. solid side locks anymore because of the newer, more accurate side locks that use roller bearings.
Skilled mold makers are hard to find and should be busy making cores and cavities, not sprue bushings and ejector plates. Do what you are good at and let somebody else do what you are not good at.
