Swiss Precision Machining for Parts with Long Length-to-Diameter Ratios
Parts with high length-to-diameter ratios are inherently challenging to machine. But at our AS9100-certified shop, we’re experts at crafting long, thin, precision parts for aerospace, medical, and armament customers. This part below is 10” long and less than ⅞” diameter giving it an approximate length to diameter ratio of 12:1!
The Challenge: Precision Machining Long, Thin Parts
A traditional lathe works well for standard parts, holding the rotating workpieces fixed at one or both ends. However, parts with a high length-to-diameter ratio can cause severe deflection (bending) in the lathe tool, making it difficult to achieve tight tolerances.
While adding a center tool to the lathe can provide the support a long workpiece needs, centers won’t do the trick on very thin and long parts—especially when dealing with a hard material that’s even more prone to causing deflection.
If you’re using a hard material and your part has a length-to-diameter ratio higher than 5:1, Swiss precision machining is the best solution.
The Solution: Swiss Precision Machining
In the hands of United CGTR’s skilled operators, our Swiss screw machines are capable of achieving precision features and tolerances on a variety of complex parts:
Parts up to 1.25” in diameter
Small parts such as pins, plugs, screws, shafts, and studs
Parts with long length-to-diameter ratios
If you’ve never seen a Swiss screw machine in action, imagine feeding a 12’ bar of material into the long, narrow bed of the machine. As the material enters, a guide bushing stabilizes the bar and ensures all cutting occurs close to the support point, enabling excellent precision.
When we’re making small parts, the Swiss screw machine can cut part after part as the bar feeds through the machine, dropping each completed part onto a conveyor, which carries them out to the end of the machine bed.
On the other hand, when we’re making very long parts, there are some additional considerations:
1. Thin or tapered parts
In most cases, the bar stock pushes the completed part clear of the machine heads before the machine begins cutting the next part. However, with very thin or tapered parts, the narrow, pointed ends can cause the workpiece to slide over or under the newly made part, jamming the machine and ruining the parts. Picture the difference between a thick, rigid log and a thin, flexible twig; the larger the diameter, the more easily the bar can push the completed part out of the way.
We resolve this issue with thin or tapered parts by manually removing each part as it is completed. Though this added step slows the Swiss precision machining process, it’s a small price to pay for precision.
2. Extra-long parts
When a part is very long—perhaps 15-24”—the leading end will become unstable as the part moves through the machine. It’s essential to support the completed end of the part as the trailing end is machined, or the completed end will move around. If the part begins to wobble or bounce as it’s being machined, the resulting deflection will compromise tolerances and feature placement.
Again, visualize the contrast between a thick, rigid log and a thin, flexible twig. A long part with a larger diameter will be less prone to deflection than a long part with a small diameter, but both types of parts still need to be held securely in place to ensure accuracy and precision.
To support the entire length of extra-long parts during Swiss precision machining, United CGTR captures the part in a tube.
Examples of Long, Thin Parts Made by United CGTR
We commonly make two types of extra-long, thin parts using Swiss precision machining: grounding rods and satellite antenna components. These parts often have small grooves with precision width-and-depth diameters and precision locations.
The satellite parts are made from high-grade, aerospace-quality copper valued at approximately $1,000 per ounce! With such expensive components, there’s no room for error. Because of our expertise in Swiss screw machining parts with a long length-to-diameter ratio, you can be confident that every part you receive is made to your critical specifications.
Ask for Swiss Precision Machining at United CGTR
Our Swiss screw machines are equipped for “lights out” manufacturing, providing ultimate efficiency for qualified productions. We can even perform turning and milling within the same machine, streamlining your services and shortening your lead times.
For parts that also require centerless grinding, thread rolling, or wire EDM, our hybrid manufacturing services provide optimum quality and cut lead times by as much as 50%!
