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Custom Workholding … Beyond the Normal

Custom Workholding … Beyond the Normal


What is custom work holding? In its simplest form…custom work holding is whenever you alter standard work holding equipment in some way to better hold a specific part.

Custom work holding becomes even more important in today’s manufacturing world with its new machine technologies that allow you to mill/turn/drill and tap in one setup. When you are trying to do more in one setup, you are also taking other possible work holding areas away…and this is where custom work holding comes in. Custom work holding goes way beyond simply altering standard equipment This is an important reason to look at the advantages and disadvantages of both manual clamping and power clamping…including the reasons for choosing one over the other.


Hydraulic Power Clamping Fixture With Multiple Parts


Custom work holding is an art.

It is a combination of good basic engineering and many years of experience in what works best with the application of the latest technologies. Sometimes what seems to be the obvious way to hold a part is not the best way. And this is determined by experience. As an example, you have a casting drawing and the same drawing is used for two or three different materials. Normally, the easiest way to hold a casting is with custom form-fit chuck jaws. The castings, even though they are made from the same drawing, will be different due to their being of different materials. Therefore, instead of making simple form-fit chuck jaws, you design chuck jaws with adjustable inserts which can accommodate the different materials. Experience has proven that different materials will vary enough that simple form-fit jaws will not work.

When should you be considering custom work holding?

There are several reasons to consider.The most obvious is to increase production. Next is to improve quality. Many times the two go together. The third reason is not quite so obvious…to reduce operator-handling of the work piece. Another reason could be reducing the number of operations required through better work holding.


Automatic Index Chuck For Parts With Multiple Sides


There are many different type of custom fixturing which can be applied to almost any situation. Some examples are special collet chucks that allow running at higher speeds than standard chucks. If you want to maintain the versatility of a chuck, counter centrifugal chucks are available for higher speeds. As are pull-down chucks, compensating chucks and both manual index or automatic index chucks. Also, there are adjustable modular fixtures to hold many different parts and tombstone type fixturing that can be either manual or power clamping. Sometimes a family of parts will have a common area for gripping which allow the same fixturing for the whole family …thus, greatly reducing the fixturing required.

Is custom work holding the most practical way to go?

Which type of work holding, manual clamp or power clamp, is best for your situation? For relatively low production parts simple manual clamp work holding is usually adequate …and for high production parts you should consider using power clamping for speed and repeatability.

Manual custom work holding generally has the advantage of being less expensive than power work holding. The disadvantage is that you are depending on the skill of the operator to properly load and clamp the work piece. This usually will take a longer time than power clamping and it is harder to control quality.because you are depending on the skill of the operator.

Power clamping, while it has the disadvantage of being more expensive, has the advantage of faster loading and more consistent gripping which provides better quality control. With the possibility of robot loading, operator involvement is almost completely removed Power clamping does have the additional disadvantage of requiring additional maintenance. Both types of custom work holding have their place. Which is better to choose is sometimes very difficult especially when production volume is in-between low and high.

How do you decide which type of custom work holding to choose?

As stated previously, there are many different options available. When Royal Machine & Tool Corporation’s Engineering Department receives a request for custom work holding, the project is first reviewed with the customer to determine his goals. At this time, a quote is provided with our recommendation on which type of custom work holding to use. If the part to be held is to be turned, we may recommend a collet chuck or counter centrifugal chuck when a high RPM is required. Should it be a multi sided part, we may recommend an index chuck. A part to be machined on a vertical or horizontal machining center would have a modular fixture, quad vertical combination fixture, special manual tombstone fixture or a power clamp tombstone fixture.

How Custom Work Holding Orders are Quoted and Processed.

Once our customer decides to proceed with the project, an order is placed. Before proceeding with full designs we will again review the project with our customer to be certain that nothing has changed to affect the quote. Full design, approval prints are then prepared and sent to the customer. At this point a final review is held with the customer. After approval, the full design is finished and manufacturing begins. Occasionally at this late date a customer will come to us with changes. These are reviewed to determine how they will affect the quoted price. When manufacturing is completed, the work holding is tested before shipping. The final testing is always conducted at our customers’ onsite facility.

In summary, each custom work holding project is unique. Many techniques and innovations have been developed through years of experience. This is where the experience of a custom work holding manufacturer is beneficial and can be usually applied to a project. Adding truth to the old adage “there is nothing new under the sun.” Custom work holding, when properly applied, will lead to more production, better quality control and less operator involvement. And will allow you to become more competitive in today’s ever changing economy.

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