Metal Cutting Corporation was founded in 1967 and moved to their current 52,000 square foot manufacturing facility in 1998. In 2008 they expanded their existing machine shop capabilities with Haas and subsequently Citizen turning equipment, allowing them to offer multi-axis CNC milling, lathe and automatic Swiss style machining up to 7 axes.

Their specialty has always been small diameter parts made from all metals.

"The parts can be long but are most often short, often very short."

When the company started in the late 1960's they  primarily worked with non-ferrous metals, especially tungsten and molybdenum. So much so that  in 1984 they became the exclusive North American distributor for Nippon Tungsten Co., Ltd.’s tungsten and molybdenum products. Since  the the 1980's they have been working with and machining more stainless steel and now have a developed a deep knowledge of machining the newer nickel and titanium based alloys.

Over the past several months Rich has been able to apply the Microcnic system to several other products that they make in their Citizen Machines.

Workholding Advances
Medical parts are often delicate, which can create problems when they are picked off with the subspindle for backwork. It is important but difficult to apply just the right amount of pressure to hold the part in the subspindle. And once the optimum gripping force is determined, it is not easy to communicate to other operators how the adjustment was made.

​Machine tool accessory maker Masa Tool Inc. (Oceanside, CA) has developed a collet system that makes this process easier. The collet is set using a special tool with marked graduations that enable precise adjustments to the gripping force of the collet.

“You can document the micrometer-like adjustment for the collet closure in your setup plan,” said Matt Saccomanno, CEO.  “It’s done the same way every time, regardless of operator skill and without relying on feel.”

One of the more challenging Swiss applications is making dental implants because of their small size. Saccomanno said that Masa recently helped a customer broach a dental implant on the subspindle with the Masa collet system holding only a small land. Considering how much force is applied to the workpiece during a broaching operation, this might have seemed impossible to accomplish.

The reason it is possible is that the Masa collet system applies the gripping forces directly over the area where the collet grips the part. The collet system has two main parts, a cartridge that replaces the standard machine collet and a smaller collet made by Masa that is installed into the cartridge. These components are held to a high accuracy and are made by Masa with proprietary grinding methods. Concentricity variation is held to 0.0002″ (0.005 mm).

“This particular broaching application used an over-grip collet,” Saccomanno said. “The process change moved an operation from the main-spindle to the subspindle and so allowed some simultaneous machining not possible previously. Before they used our system, the part was made entirely on the main spindle.”
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An over-grip collet opens up to pass over a shoulder or some other feature on a part in order to grip the part past the shoulder. Masa makes over-grip collets that can open up to 4 mm over the chucking diameter. This is the largest difference in diameter in the industry and still holds 0.0002″ TIR, according to Masa.

Make plans now to visit Masa Tool at the  IMTS 2016 Booth W-2232 and learn about our new Microconic Workholding System.

The Microconic™ work holding system is a mechanically actuated micro-workholding system for use in high precision, small diameter CNC turning applications.

The system consists of two major components: The Microconic™ cartridge, replaces the standard TF20 collets and  fits into your CNC machine with no modifications to the spindle required.  The second component to the system is the  Microconic™ collets which have capacities of 0,22mm - 10,00mm ( 0.0086" - 0.3949") and -Over-Grip collets which can open up to 4mm over the chucking diameter and run within 5 µm/.0002" TIR

It's the first and only workholding system for the micro-machining industry.

Avinger Inc., based in Redwood City, California,  designs, develops and manufactures precision medial device technology with the goal of helping patients keep their legs. Recently they began testing the Micoconic system on their Citizen L20 (7M8) Swiss Screw Machine using a Utilis 3000 series cutoff holder and an 1/5mm X 10mm insert.  The bar stock was .225" OD round.

They where kind enough to share their test results with us. 

A Swiss CNC machine shop presented us with several problems related to long cycle times and poor tool life  with a high-volume group of  Dental Surgical Drills, Taps, and Counterbore Drills with standard ISO shank configuration.  

Before implementing the Microconic solution there were a number of problems:

• The cutting edges would be damaged by contact with the pick-off collet.
• All operations had to be performed in the main spindle because the part could not be held rigidly enough in the sub-spindle. This made for a very long cycle time.
• The milled flat and groove operations on the shank end had to be finished in the main spindle because of the lack of rigidity & lack of concentricity in the sub spindle
• The cut off tool took a beating due to the interrupted cut at the milled flat.  The cut off tool had to be sharpened or replaced every 60 pieces.
• Due to high tool maintenance and frequent adjustments, these jobs required a skilled setup person to run this product with little time to spend elsewhere. 

Our customer was machining 6Al4V Titanium dental implants and scrap rates increased the longer our competitors collets where in use.  

This root cause was primarily result of cutting the threads in the main spindle.  Chips wrapped around the finished threads before the implant was handed over to the sub spindle collet for machining of the head hex and internal thread.