One chuck does the work of many

Latest chuck developments for automotive use include one that eliminates the requirement to use several different chucks in one operation and one for milling crankshafts.

If any part of the engineering seeks constant innovation, cost reduction and productivity improvements it is the automotive industry.

Halifax-based Pratt Burnerd is one of the premier suppliers of workholding to the automotive industry, mainly due to its ability to provide innovative solutions to complex problems.

In addition to its standard range of workholding products, it offers both special and standard products, many of which have developed from creating a "special" for automotive applications.

Most recently it has developed both a new chuck to eliminate the requirement to use several different chucks in one operation and a chuck for milling crankshafts and it is currently introducing a new-style chuck to machine wheel hubs in one set up.

The new chuck from Pratts has been designed to reduce scrap by improving component quality and therefore increasing productivity.

Again developed in response to a specific problem, the new chuck is available from within the standard product range.

A customer was using several chucks, each with a number of jaw changes.

These have been replaced by one Pratt chuck, capable of accepting up to 40 different sizes of component.

Set up and truing is much quicker and more accurate, in addition to which because only one chuck is used, repeated checks for concentricity do not have to be made.

Pratts believe that nothing else like it is available on the market.

The new crankshaft chuck is an unconventional solution to production requirement not normally dependent on chucks.

It was developed in response to a request from an automotive supplier which wanted to improve productivity and minimize the space requirement.

The new chuck, which reduces a typical body length of 500mm to 150mm, is suitable for use on forgings and castings and is factory-sealed so is ideal for high volume work.

A Pratt chuck is placed at either end of the crankshaft, permitting the crank to rotated at up to 60rpm.

An extendable centre allows the crank to be loaded automatically - the chuck clamps onto the centres and the jaws align onto the crank.

Clamping jaws can then clamp onto the bearing journal allowing the diameters and sides of the pins to be milled simultaneously.

Once the chuck is orientated onto the lobe plate, the aligning jaws can be retracted to allow journal to be machined.

Using the Pratt chuck increases productivity significantly whilst also reducing costs substantially.

Currently, the company is introducing a chuck designed to improve the efficiency of wheel hub manufacture, developed in response to a German manufacturer.

The wheel hubs are pressed out of aluminium castings to form the correct grain structure but the component at that point of production is slightly out of round.

Only a very small part of the component can be clamped and machining must be in one operation to maintain precision.

Thin section aluminium so force of alignment distorts wheel.

Pratts have developed a 2+2 chuck to align the wheel hub, using two jaws to align onto one axis and then two to align onto the other in order to centralize the component prior to machining.

At the same time, a different 2 jaw pull back and clamp onto an internal flange.

Once clamped with the 4 clamping jaws the aligning jaws are released automatically.

This system prevents the clamping forces from distorting the component.

A similar chuck is used for the second operation on the wheel hub (to machine visible face of wheel), clamping onto an outside diameter rather than the inside diameter.

The second op is cosmetic rather than functional so quality of the surface finish is also critical.

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