From Bridgeports To CNC Milling Machines In A Few Short Years

It only took a few years for CNC milling to totally take over the workload in tool shops around the world. Not much stays the same for very long, and this certainly holds true for plastic injection moldmaking.
Once upon a time a guy could (and many did), start a moldmaking shop in his garage with just a Bridgeport milling machine, a surface grinder and a lathe. With a few accessories he could build just about anything.
The old manual mills had many attachments: Volstro heads, rotary tables, Cherry pickers, broaching attachments, cross-slides, special boring heads to do flat bottom work, dividing heads and all kinds of things that no longer have any practical application.
What happened: CNC milling machines, that’s what happened. I personally recall when I was given my first mold to build by myself. I was excited and looking forward to making everything on my own. Once I got my cavity blocks, slides and gibs milled and ground to do finish work, the owner came up with a little tool cart and informed me that they were going in the new CNC machining center. What a disappointment!
I got the feeling like I was going to become obsolete soon, so I decided to focus on grinding, which appeared to be extremely difficult to replace with any type of CNC. I was mostly right, thankfully.
Vertical Machining Centers (VMC)
The vertical machining center, or VMC, is one of the workhorses of any tool-and-die or mold making shop. Jobs that used to take days now can be done in hours. The accuracies are greater than ever, as are the finishes.
Programmers has access to cutters of any imaginable type, from solid carbide to insert cutters to special carbide form cutters. Companies are developing new coatings for carbide cutters, enabling the milling machine to cut faster, more precisely and with better surface finishes.
With the use of pallets and robotics it is feasible to run 24/7 unattended for days at a time. The ability to run lights out, overnight and on weekends often provides the edge over the competition that gives one company an advantage over another.
Horizontal machining centers (HMC)
Europeans have long used universal milling machines that can quickly be changed over from vertical to horizontal. This is a great feature because the machining done horizontally is more rigid than vertically and the stock removal rates are far greater as well.
With a CNC horizontal milling machine plates, such as mold base plates, can quickly and accurately be machined. These machines can also work in a similar manner to a boring mill, with 5 sided machining commonly done.
High Speed Milling Machines
Nothing can rival a high speed milling machine when it comes to EDM electrode manufacturing. Specialize machines with negative pressure chambers and laser tool-setters can produce both graphite and copper electrodes quickly, cleanly and accurately.
Another common application of the high speed machining center is for hard machining. Hard machining can eliminate a great deal of EDM and surface grinding work, saving time and money.
Special carbide cutters have been developed specifically for use in a high speed milling machine.
The high speed spindles and rapid feed rates produce an extremely fine finish, often eliminating subsequent mold polishing. The fine details normally done by the sinker EDM are often now machined on these amazing machine tools.
5 Axis-Milling Machines
Remember those Bridgeport milling machine attachments mentioned earlier? The 5 axis milling machine replaces all of them. Now it is possible to do 5-sided machining in one set-up, with no operator intervention.
When coupled with pallets and robots these machines can run unattended 24/7 for days on end. With the newer software, the programming has become easier, thus enabling the shop to funnel more and more work through these machines.
Conclusion
CNC milling is central to any mold making shop and should be supplied with the best solid carbide cutters, indexable end mills, carbide insert cutters, toolholders, shrink-fit equipment, inspection equipment and CAD/CAM software.