What Are the Differences between Conventional CNC and Swiss Machining?
Will conventional CNC machining solve my problem, or do I need CNC Swiss machining? What’s the difference between the two?
There are distinct advantages and applications for both, but they are very different processes. Choosing which precision machining process depends on the specific job.
CNC Swiss Machining
Swiss-type precision machining provides a cost-effective way to produce components for medical and defense products such as dust cover pins and firing pins used in military rifles. These long, slender components feature a tolerance band of 0.0005 inch on the part’s diameter.
A Swiss-type lathe consists of a variety of turning machines that feed the stock through a guide bushing. This means the OD turning tool can always cut the stock near the bushing, and therefore, near the point of support, no matter how long the workpiece. The machine feeds the work out of the spindle and past the tool as it goes. This makes the CNC Swiss-type particularly effective for long and slender turned parts.
Advantages of Swiss Turning Process
The advantage of a Swiss turning process is that the material is supported close to the tools that are cutting, using a guide bushing that the bar stock is pushed thru and into the tools. This prevents deflection of the bar stock when using a conventional turning process. On many machines, the tools are only a few thousands from the face of the guide bushing.
- Swiss-style screw machine, running off bar stock, typically creates a cylindrical part
- A 12-foot bar with automatic bar loaders in which 15-20 bars can be placed and fed through the machine
- The tools are machining as the bar is pushed forward through a guide bushing
- There are often numerous tools and multiple axes that can be used to complete the part
- Swiss machining can deal with complex designs and complex parts can be machined to completion on one machine
- Small runs from 1,000 pieces to high-volume production can be done through Swiss machining
- Processes can include drilling, turning, milling, boring, knurling, and many special processes
Swiss turning is ideal for long parts and small-diameter parts under .125″.
Examples of Swiss Parts Are:
- Contacts used in connectors
- Watch parts
- Long medical devices and implants
- A variety of connecting components for aerospace and electronics
CNC Conventional Machining
The first CNC precision machines were built in the 1940s and 50s and became the workhorses of the modern machine shop. Motion is controlled along multiple axes, normally at least two (X and Y), and a tool spindle that moves in the Z (depth). The position of the tool is driven by motors through a series of step-down gears, in order to provide highly accurate movements, or in modern designs, direct-drive stepper motor or servo motors. Open-loop controls work as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines, closed-loop controls are standard and required in order to provide the accuracy, speed, and repeatability demanded.
Advantages of Conventional Turning
Conventional turning extends the material from the chuck/collet to the overall length of the part, and then tools will move into the bar. Conventional turning is better suited for short, large-diameter parts with very tight tolerances. Conventional turning is also best suited for larger parts with difficult materials.
CNC-like systems are now used for any process that can be described as a series of movements and operations. These include laser cutting, welding, friction stir welding, ultrasonic welding, flame and plasma cutting, bending, spinning, hole-punching, pinning, gluing, fabric cutting, sewing, tape and fiber placement, routing, picking and placing (PnP), and sawing.
Conventional Turning Distinguishers
- CNC machining is ideal for forgings, castings, plates, or blocks of steel
- The use of higher production, special fixturing, and palletizing systems are created to facilitate the volume efficiently
- Tool changers in the machine store multiple tools, and the machine picks a tool for the operation, puts it back, picks the next tool and repeats the process until the product is machined to a finished state
- Fixtures can hold any number of parts from approximately one to 40
Examples of Conventional Turning Parts:
- Fluid controls
- Anything with a diameter larger than 1.5″
The job, materials, and ultimate use of the part are the drivers in which process you should use. CSI Group and our partners have 26 years of experience providing one-source solutions for your micromachining needs.