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Image is Everything

In medical machining, it’s all about cosmetics. The appearance, look and feel of the part must compare – or exceed – the finest automotive detail.

Posted: February 8, 2008


In medical machining, it’s all about cosmetics. The appearance, look and feel of the part must compare or exceed the finest automotive detail. Check out how this company hits tolerances right on the nose and surface finishes that would make some companies shiver.

We have one plant in Niles, IL and another in Elk Grove, IL. Each occupies about 2,000 sq ft. Of our 76 employees, 60 are directly employed in production. Our annual revenues are just under $10 million and our growth plans are currently for about 10 percent a year.

We’re relying on continued growth in the medical industry and, from what we can tell, it’s there. None of us is getting any younger, and they’re doing some amazing things in medical. When the backbone of your operation is in the medical field, you’ve got to be able to perform perfectly, repeatably. You must hit tolerances right on the nose, with surface finishes that would make some companies shiver.

The materials we process are steel, stainless, heat-treated steel. All of our work is very tight tolerance, with extreme finishes. For example, we do a 3 in long medical housing with a diameter of 1.125 in that holds transmission components for orthopedic instruments. This housing is probably one of our larger parts, with many very close tolerance bores on its interior.

This part requires milling on two sides, which we perform in the same operation on our Hardinge Quest 8/51SP lathe. This reduces three processes down to one. We turn, drill and bore one side of the part, then transfer to the sub-spindle and do all the back-end work on the same part. If we attempted this without a sub-spindle, we would have to remove the part manually, turn it 180 deg and possibly re-fixture it in the lathe to finish it there.

A pretty complex part run on this lathe, one having a number of features we want to complete start-to-finish in one operation, has a typical cycle time of 10 min to 15 min. Our 8/51SP features rapid traverse rates of 1100 ipm in the X-axis and 1500 ipm in the Z-axis. Turret index time is 0.1 sec with a capacity of 12 tools (with VDI 30 top plate).

Our live tooling, Y-axis, sub-spindle, and C-axis on main and sub-spindles allow us to do true milling of prismatic parts complete. We do rigid tapping on the main spindle and cross- and face-working operations with the live tooling. We can program exact synchronization between the main and the sub at any rpm for part transfer for secondary machining operations.

Our live tooling on the VDI top plate is capable of machining on both the main and sub-spindle. The Y-axis permits thread-milling and complex off-center milling and drilling operations on the main or sub-spindle. C-axis on both main spindle and sub-spindle provides positioning in increments of 0.001 deg. Three dimensional contouring, complex round and prismatic machining, square shoulder and lettering are accomplished by synchronizing the spindle with the X- and Z-axes.

Since the lathe does not require a spindle adapter for using collets, we have a larger machine area with a bar length capacity of 24 in. Our programmable resolution/tool offset capability is 0.000010 in. Our spindle configuration is A2-6.20C, with a through hole of 2.378 in and chuck size of 8 in. Nominal work size with collet is 2.00 in OD x 24.00 in L. X-axis travel is 7.45 in and Z-axis travel with collet is 24.00 in. We can achieve 0.000020 in on part roundness and an 8 µin surface finish.

The 8/51SP is a perfect match for the parts that we run through the machine. Most of our parts are smaller, and the spindle size on this lathe permits us to run 1.625 in to 2 in which is the size of bar stock we’re running through it. We can chuck parts in the machine using a collet, and the spindle runout and concentricity are right on the money. On another job, we use a Hardinge Quest GT275SP as the second lathe in a lathe/lathe/mill cell to run drives and shafts for power tools in medical applications, along with other housings.

This lathe has a unique gang-type tooling plate that holds all the tools. We can remove the entire plate, save the job with all the tool settings unmoved, put in a different pre-set tooling plate for the next job, touch off the new plate, and we’re up and running our next job. Our set-up time dramatically reduces when we change the tooling in and out that fast. Our typical cycle time on the GT275SP is usually three minutes or less.

The parts we run on the GT are all stainless steel and some are heat-treated stainless that are even tougher on the machine. Working with these materials requires a very rigid, reliable and precise machine ? which is why we ordered two GTs in the last year. We can achieve surface finishes of 8 µin and exacting part roundness of 0.000015 in on this lathe, plus a continuous machining accuracy of 0.0002 in. The 5-hp spindle drive motor achieves 3.5 sec spindle acceleration from 0 to 8000 rpm and 3.5 sec deceleration from 8000 rpm to 0.

This lathe has a precision collet ready spindle with 1.0625 in bar capacity for quick spindle tooling changeover. Combine this with the interchangeable tooling top plate and we drastically reduce our set up and non-cut time. Pre-tooled top plates can be removed and interchanged under a minute within 0.0002 in. The top plate accommodates up to 12 tools for small diameters, and tools can be added or removed from any location without disturbing any other tools.

Our rapid traverse rates are 708 ipm on the X-axis and 945 ipm on the Z-axis. Absolute encoders and preset servo drive positioning eliminate the homing sequence for X- and Z-axis. The 1,800 lb HARCRETE® polymer composite base provides stability, machine damping and extended tool life. Our idea behind purchasing the new 8/51SP and two GT27SP lathes was not to spread out into different markets.

Our position is to invest in such a fashion as to strengthen, solidify and maintain our current place. These machines have kept us competitive and allow us to grow stronger in the medical field. It’s taken 10 to 15 years to really understand what medical wants tolerances in the 10ths and finishes of 16 to 32 (spelled out right on the print). They won’t accept anything less…and why should they?

Paul Prikos is the vice president of X-L Engineering Corporation, 6150 West Mulford Street, Niles, IL 60714, 847-965-3030, Fax: 847-967-6373,, Hardinge Inc., One Hardinge Drive, Elmira, NY 14902-1507, 607-734-2281, Fax: 607-734-8819,,

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