Precision Surface Grinding In Injection Mold Making

I have heard the same story so many times: precision surface grinding is obsolete. The use of manual surface grinders is a thing of the past, etc.

The odd thing is that there are always injection mold makers standing there performing precision surface grinding when this is said by the salesman who is showing clients through the shop!

It is true though that WEDM has replaced a huge amount of precision surface grinding. Anyone I know is very thankful for this! Not many people miss the days of elaborate setups required for contour grinding, for example.

How is precision surface grinding used in injection mold making?

First, there should be a distinction between manual surface grinding and hydraulic surface grinding. For the purpose of this article, manual surface grinding means the grinding of mold components, such as core pins, slides, lifters, core and cavity details, etc. Hydraulic surface grinding refers primarily to squaring up blocks and plates for subsequent machining, such as CNC milling.

Some common applications of manual surface grinding are:

• Finishing shut-offs on core and cavity blocks
• Making lifters
• Finishing core pins and inserts
• Electrode manufacture
• Ejector pin grinding
• Finishing slides and cam blocks
• Squaring up small inserts and blocks after heat-treat
• Removing tabs and finishing heels on WEDM'd inserts

Why apprentices should do a lot of precision surface grinding

Precision surface grinding gives the mold maker an appreciation for the finesse required to finish a quality injection mold. The leap from good to excellent is huge. The apprentice learns proper set-up procedure, cleanliness, how to handle precision tooling correctly, the direct application of trigonometry, and how to focus on the machining of mating parts.

Another good effect of precision surface grinding is the humility gained through trial and error. Many cocky apprentices have been brought down to earth in the grinding department!

Why companies should invest in high quality manual surface grinders

In these days of CNC everything, it might seem unproductive to invest in high quality manual surface grinders.Even by buying a lesser expensive machine, such as a Kent surface grinder, or Harig surface grinder, at least the mold maker does not have to fight the grinder to obtain good results.

On the other hand, buying a Mitsui surface grinder, or even an Okamoto surface grinder can make the work of your best toolmaker much easier. Investing in good quality digital readouts and a good suction system makes all the difference!