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Tombstones keep spindles alive: fixturing plays an important role in manufacturing heat exchangers, and tooling columns on pallets keep machining-centre spindles running full tilt.

Heat exchangers are merely pipes full of tubes, but packed with engineering, according to ITT Standard, Buffalo, NY. The firm makes the BCF line of heat exchangers, said to be the first mass-produced, fully standardized, small heat exchangers.

Even though heat exchangers are mechanically simple devices, their proper design requires knowledge of thermal and fluid flow, material compatibility, and heat-transfer parameters of components in limited space. Efficient design depends on expert engineering, computer technology, and quality manufacturing.

At ITT Standard, Edward J Blasz, manager, manufacturing engineering, is responsible for turning the designs of many varieties of heat-exchanger components into products that meet tight blueprint specifications. He builds special fixtures to get the job done on the wide variety of work required, and the fixtures are largely based on tooling cubes, sometimes called tombstones.

Setup for JIT

You often think of tooling columns or cubes for use with modular fixturing, but these primary components act as permanent bases for simple hard fixtures and clamps. The columns are fixed to pallets, and operators load workpieces onto custom-made tooling plates or fixtures pinned and screwed to the columns. The pallets are on track outside the machining station, and they exchange quickly, maximizing cutting time.

Ed Blasz says, "We use three different kinds of products from Stevens Engineering Inc: a Silo Column for tooling plates, narrow-profile angle plates for odd jobs, and several types of double-access angle plates. We set up to hold several different sizes on one face; and, of course, there are four sides of the Silo to use.

"We designed special plates to mount on the tooling cubes, and we use the fixtures to handle one-piece orders, JIT-sized orders, and even mass-produced parts for our own product line."

Much of the work is done on a Mazak H500-50 horizontal machining center. Mr Blasz ordered big tooling plates so engineers could mount several workpieces on each one. He says, "We don't change the tooling plates. If we have a demand for, say, a 10" part, we have a couple different locations on each column where we can mount it. All the operator has to do is bring the pallet to the loading station and load the 10" areas on the tooling plate, then run the pallets into the machine. Of course, the machine is running other parts while we're loading the fixtures."

Mr Blasz adds, "We make up tooling plates that mount onto Stevens double-access angle plates. The tooling plates adapt to two or three different parts, and we can add another fixture on top to accept an additional part." The key is to minimize setup time on the small-quantity runs.

High-volume work

A Mazak H400 horizontal machine also benefits from tooling cubes. The machine handles an entire product line involving brass, cast iron, and stainless-steel parts. Here, the firm uses two different styles of tombstones from Mid-State Machine Products. On one, Blasz mounts 8" parts on one side, and 3" parts on the other side. On the second, he mounts 4" and 6" parts.

A special fixture designed by ITT Standard engineers employs three custom mounting fixtures to hold bonnets. These provide secondary fixturing for different components. Carr-Lane clamps hold many of the workpieces in other ITT-built fixtures.

Thanks to the tombstone-and-pallet concept, engineers can interrupt a larger order and put through a request for a special job with minimum delay. The cubes facilitate a good mix of high-volume and special-order work--JIT machining at its best. T&P

For information on modular tooling from Stevens Engineering Inc, circle 378. For information from Mid-State Machine Products, circle 377.
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Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Author:Miller, Paul C.
Publication:Tooling & Production
Date:Aug 1, 1993
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