Grippers

Grippers are found at the end of the drawbar just inside the tooling taper. There are several manufacturers and they vary in design from BT, Cat and HSK to name a few. It is important to make sure your gripper fingers are in proper running order. They will wear from use and poor condition can cause the following:

-Tool holder misalignment
-Poor retention force
-Tool dropping during operation
-Missed tool changes
-Stuck tooling
-Poor part finish
-Premature tool wear
-Tool holder damage

Most gripper fingers can be replaced in the machine if needed. Some systems require the removal of the drawbar but the effort is well worth the cost savings.

Belleville Washer

The Belleville washer is the most common source of spring tension in drawbar systems. They are similar to flat washers except they are cupped. They are placed on the drawbar in sets that comprise equal numbers of washers in opposing orientation. For example 10 sets of 3x3 would mean 3 washers cup side up against 3 washers cup side down 10 times. When placed on a drawbar and compressed they provide thousands of pounds of spring force.

Belleville washers do have a service life of so many cycles. After they have reached this lifespan they begin to loose spring tension and eventually break. This causes low drawbar force and should be avoided.

Spindle Drawbar

The spindle drawbar is used to hold the drawbar assembly together. The grippers are attached to it and the Belleville washers ride on it. It is important to make sure the area where the Belleville washers sit is smooth and burr free. This area will wear with use and when this happens the Belleville washers can no longer flex properly and get hung up on the drawbar. This can cause low drawbar force and eventually failure of the drawbar system.

Drawbars can be ground plate ground to repair them. Northland Tool & Electronics also manufactures replacement drawbars for some of our repairs.

Spindle Drawbar

The spindle drawbar is used to hold the drawbar assembly together. The grippers are attached to it and the Belleville washers ride on it. It is important to make sure the area where the Belleville washers sit is smooth and burr free. This area will wear with use and when this happens the Belleville washers can no longer flex properly and get hung up on the drawbar. This can cause low drawbar force and eventually failure of the drawbar system.

Drawbars can be ground plate ground to repair them. Northland Tool & Electronics also manufactures replacement drawbars for some of our repairs.

Integrated Coromant Capto spindle clamping system

This system is fairly new to the spindle design world. It is used primarily in Capto tooling applications. This drawbar type can not be rebuilt if it falls out of specification it must be replaced with new. Yes it kills me to say that!