Category: Part: Surgical Drills

Shop improves Dental Surgical Tool Production with Microconic Over-Grip Collets

1/12/2022

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.

These surgical components are made from 465 SS, 17-4PH, and Titanium. The shop makes them complete with cutting edges on a Swiss-type CNC turning center.

Due to the complexity of the cutting edge configurations, they are machined entirely on the main spindle, with the cutting edges out first. In all cases the cutting edges are larger in diameter than the shank.

Before Microconic: The Workholding Problems

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.

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Masa Tool Introduces the Microconic™ Over-grip Collet

5/20/2015

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Masa Tool has developed the Microconic™ system specifically for holding workpieces from Ø0.15mm to 10mm (Ø0.006" to 0.390") in any machine that has a collet-type chuck. The system consists of two major components: The Microconic ™ cartridge, which fits into your CNC machine spindle replacing the standard 5C, 16C, TF15, Tf16 TF20 , TF25 or TF37 collets, and the Microconic™ collet, which fits in the Microconic ™ cartridge.

Part of the standard offering of Micrconic™ collets is the UM10W Over-grip series. The UM10W over-grip series is offered in the coverage range from Ø0.5mm - 7.2mm diameter (Ø0.020" - 0.283").

Microconic™ Overgrip Collet. A = Grip Ø, B = Largest Part Ø, G = Grip Land Width

Over-grip collets, also referred to as over-the-shoulder collets, are used in a pick-off /sub-spindle when it is required to clear a shoulder and grip on a smaller diameter beyond the larger diameter.

The Drill blank pictured at the left is a good example of this kind part.

Extra spread is required to open the collet wide enough to go over the larger diameter. The grip diameter (A), the width of the grip land (B) and the largest part diameter to reach over (G) are required to choose the off-the-shelf over-grip collet for your specific part.

Microconic™ Over-grip collets are a great way to expand your CNC machine's capability and reduce cycle time.

The Problem
Generally, pick-off collets grip short part lengths that only occupy the front section of the bore. All of the clamping force is on the collet angle, which is a considerable distance from the part being held. As a result the collet begins to collapse under the angle.

At that point, the bore is no longer parallel and does not squarely grip the part. This usually results in the parts running eccentric and slipping in the collet. At that point machine operators generally increase the clamping pressure in reaction to the runout. This eventually results in the premature failure of the collet.

Another problem that is peculiar to pick-off collets is that they are sometimes closed without a part in place. Having no internal resistance puts undue strain on the collet walls, which can contribute to premature collet failure.

Microconic Over-grip collet opens over bone screw thread to hold the workpiece on the shoulder.

Machinable Brass ejection guide sleeve blank installed in the back of Microconic Over-grip collet

Microconic UM10W Over-Grip collet

The Solution

Over-grip collets from Ø0.5mm - 7.2mm diameter (Ø0.020" - 0.283").
Opens up to 4mm (0.157") diameter larger than the clamping diameter. Some restrictions apply to larger sizes approaching the 7.2mm (0.283") max diameter
Grips with the same industry-best rigidity and accuracy as our standard collets.
Compatible with all Microconic M10 cartridges: F20M10, F25M10, 5CM10 & 16CM10.
Fatigue tested design to over 250,000 full-load cycles.
Microject™ Brass ejection guide sleeve blank is included with each Microconic™ over-grip collet.
All sizes available to ship in 2 days.
Reduce part cycle time by moving operations to the sub spindle that you might currently be performing in the main spindle.

Microconic™ Overgrip Collet. A = Grip Ø, B = Recessed Part Ø, G = Grip Land Width

Microconic Overgrip collet installed in F20M10 Cartridge with a typical medical part produced using the Over-grip collet

Microconic Overgrip collet and Microconic F25M10 cartridge installed in the sub spindle with standard extended nose capability.

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breaking news

Shop improves Dental Surgical Tool Production with Microconic Over-Grip Collets

Before Microconic: The Workholding Problems

Masa Tool Introduces the Microconic™ Over-grip Collet

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