What Is Swiss Machining? How It Works and Uses

Swiss machining is a precision manufacturing process used for high-precision and complex parts. It is particularly used in the production of small, intricate components like medical devices, watch parts and other precision components. It's performed on high-precision, Swiss-type lathes. The combination of a sliding headstock, multiple and semi-independent tool posts, and powered (rotating) tool posts allows higher precision than normal lathes. The method facilitates the cutting of long, thin parts with less setup constraint than normal lathes. Production of more complex geometries than with basic turning and milling is made possible, similar in some regards to 4+ axis CNC machines. Reduced waste and lower setup/production times are common and desirable advantages.

This article will discuss Swiss machining, how it works, its uses, and many more.

What Is Swiss Machining?

Swiss lathes are often referred to as Swiss machines and Swiss automatic lathes. Their main productivity strength is the ability to perform simultaneous machining operations. This allows multiple tools to work on the workpiece at the same time. Swiss machining works by applying a Z-axis feed to the bar stock through an automated chuck. This clasps the feedstock and extends it into the operational area of the device. The bar stock extends into the tooling area just sufficiently for the operational needs of one part. Immediately behind the tool application/work area, the bar stock is supported by a rotating support or guide bushing.

In a manual or CNC lathe, the workpiece is presented in a fixed-position chuck that only moves by rotation. Longer components can also be supported in a tailstock, for double-ended stabilization to reduce the bending effect of cutting forces. In contrast, with a Swiss lathe, the workpiece can both turn and move back and forth along the Z-axis while various tools cut away the features of the part. Because of the ability to present multiple tools in cooperating actions, Swiss lathes can operate simultaneously in multiple zones, whereas a traditional lathe can only operate in one zone at a time. In addition, the Z-axis positioning control combined with powered tool posts allows the machines to perform processes that involve no turning but are in effect milling operations.

What Is the Origin of Swiss Machining?

Swiss machining originated in Switzerland in the late 19th century. It was initially developed for the reduced cost/improved precision manufacture of precision watch components when Switzerland had a near monopoly on quality watchmaking. The Swiss watchmaking industry demanded highly precise and intricate parts at higher productivity and lower cost. Traditional machining methods struggled to achieve the demanded precision and productivity.

The development of the Swiss-type lathe is generally attributed to a Swiss watchmaker named Jacob Schweizer in the mid-19th century. There is no clear invention point, but this approach to the machining of precision components underwent various developments and refinements that continue today. These lathes had a Z-axis sliding headstock and a guide bushing that held and rotated the workpiece with higher precision. This design significantly reduced vibrations and the consequent surface “chatter” that resulted from less local support being applied to the bar stock. This allowed for the machining of higher aspect ratio components with tighter tolerances.

Over time, the Swiss machining technique expanded beyond watchmaking and into most precision industries such as: medical device manufacturing, aerospace, automotive, and electronics. The ability to produce complex, small, and highly precise components efficiently made Swiss machining a universal manufacturing process. 

How Does Swiss Lathe Machining Work?

Swiss lathe machining works by first preparing the workpiece. This workpiece is usually a long, slender rod of material (e.g., metal, plastic) that is fed into the machine from behind the headstock. The workpiece is inserted through a guide bushing located immediately proximal to the work area. The guide bushing supports and guides the workpiece, reducing vibrations and helping to maintain cutting precision.

A bar feeder is often used to supply a continuous length of material, allowing for continuous machining without the need for frequent operator intervention. After a part is finished, the bar feeder system releases the chuck and slides sufficient feedstock for the next part, before re-clamping. The headstock of the Swiss lathe holds and rotates the workpiece, using the main spindle drive, which provides the feedstock rotational motion.

Multiple cutting tools are mounted on tool slides or tool holders arranged around the workpiece. These tools can move independently in the X, Y, and Z directions and are of very high precision and low hysteresis. As the workpiece rotates, the cutting tools act as either single-cutter faces or as rotating multi-cutter tools. Tools perform specific steps in the overall machining operation—turning, drilling, milling, threading, or cross-drilling. The guide bushing is essential for maintaining tight tolerances. It supports the material very close to the cutting tools, minimizing deflection and chatter. Once the machining operations are complete, the finished part is "parted off" from the remaining material using a cut-off tool. Modern Swiss lathe machines are generally CNC-controlled, and programmed for: precise tool movements, feed rates, and other parameters.

What Is the Swiss Machine Used For?

Swiss lathes are generally used for small and high-value parts, high precision, high-volume manufacture, and various materials such as: stainless steel, brass, bronze, tool steels, etc.

How Is the Swiss Machine Used in the Manufacturing Industry?

In general, Swiss machines are used in two modes of manufacturing operation. In stable and high-volume setups in-house, making a limited range of parts—often dedicated to a single part made in very high volume. In subcontract machining services to supply varied clients in a batch-based production process that allows clients to access the skills and CAPEX of Swiss machining with lower commitment, at a higher per-component price.

What Other Industries Use Swiss Machines?

Any industry that requires small, high-precision components that are either turned or made by a mixture of turning and milling uses Swiss machines. For example, 

Swiss machining is used in the manufacture of medical devices such as: surgical instruments, orthopedic implants, dental implants, and catheters to name a few areas. It is also employed to manufacture critical aerospace components such as: aircraft fasteners, hydraulic fittings, and sensor housings. In electronics, swiss machining is used to produce small, high-precision electronic components such as: connector pins, sockets, and contact probes. 

When To Use CNC Swiss Machining

Swiss machining is best used for small and high-precision parts, long parts requiring small diameter operations that lose stiffness in ordinary turning, combined turning and milling parts, and higher-value and higher-volume components.

What Are the Materials Suitable for Swiss Machining?

The materials suitable for Swiss machining are:

1. Copper

Copper is extensively processed by Swiss machining for its excellent electrical and thermal properties. It's used for electrical connectors, pins, sockets, and other components in which electrical performance and heat dissipation are crucial.

2. Brass

Brass components are often manufactured by Swiss machining due to their excellent machining properties. It is widely used to produce components such as: connectors, fittings, valve bodies, and decorative parts, in which precision and a visually appealing finish are essential. Brass is widely used for its beneficial corrosion properties and excellent palatability.

3. Nylon

Nylon is processed through Swiss machining to create high-precision components for which its low friction coefficient, low density, and corrosion resistance are applicable. This includes: bushings, gears, and insulators.

4. Titanium

Small titanium components are made on Swiss machines whenever exceptional strength-to-weight ratio, corrosion resistance, and biocompatibility are required. This finds application in aerospace components, medical implants, and various high-performance parts.

5. Aluminum

Aluminum is processed through Swiss machining due to its low density, generally excellent machinability, and good corrosion resistance. The material is used to create aerospace parts, automotive fittings, and consumer goods.

6. Nickel

Nickel parts are made by Swiss machining, benefitting from corrosion resistance, high-temperature strength, and electrical conductivity. It is commonly used in aerospace, electronics, and chemical processing applications.

7. Plastics

Various rigid and engineering plastics are widely used in Swiss machining to create components for most industries. These components offer low friction, low density, low cost, and corrosion resistance.

8. Carbon Steel

Carbon steel parts are made by Swiss machining, particularly whenever durability and cost-effectiveness are paramount. This is prevalent in manufacturing components like: automotive fasteners, shafts, firearms parts, and industrial machinery parts.

How Long Does the Swiss Machining Process Take?

It depends. A similar series of operations applied to a part by Swiss machining will generally be faster than a comparable capability by traditional or capstan lathe. Multiple operations can also occur simultaneously. Similar benefits accrue in comparison with 4+ axis CNC machining, which again generally uses only a single operation at a time.

How Accurate Is Swiss Machining?

It is typically possible to maintain diametral tolerances of +/- 0.0004 mm on small and flex-vulnerable parts. This compares favorably with traditional lathes that can only approach these tolerances by extremely fine cutting and much longer processing. Part length tolerances in Swiss machines also compare well with typical lathes. However, this is a result of better machine construction rather than the fundamental principles of the machine, as longitudinal processes differ very little between the machine classes.

What Are the Advantages of Swiss Machining?

Swiss machining offers some significant advantages over other machining approaches such as:

1. Higher precision.
2. Lower chatter.
3. Longer and thinner parts can be processed faster.
4. More rapid processing results from multiple, parallel operations being applied.

What Are the Disadvantages of Swiss Machining?

The disadvantages of Swiss machining are listed below:

1. These machines are poorly adapted to larger jobs, both in diameter and length of parts.
2. The CAPEX costs of Swiss machines are generally higher than more basic equipment.
3. Operator skills in operation or programming are of a higher standard and the sector is quite skill-dependent.

How Does Swiss Machining Differ From Traditional Milling?

There are various differences between Swiss machining and the more commonly available processing methods. Swiss machining offers higher precision and higher productivity than other methods. The process is only applicable to smaller parts. Establishing production and developing good operational skills in Swiss machining takes longer and costs more than more basic tool setups. To learn more, see our guide on Traditional Milling.

What Is the Quality of Products Produced Through Swiss Machining?

When correctly set up, Swiss machining delivers very high-quality parts, with low per-part processing times and a reduced per-part cost as long as volumes/batch sizes are appropriate.

Are Swiss Machine Products Durable?

It depends. The durability of parts is a design and materials selection issue. In situations in which metal parts are not exercised beyond their intrinsic strength, abrasion, and corrosion limitations, they can serve indefinitely. Swiss machining can be applied to a wide range of materials, so no generalized description of durability offers any insight. However, higher precision can result in longer component life. Lower chatter makes surfaces that are less susceptible to wear. Lower machining stresses can result in overall better strength in delicate components.

How Much Does Swiss Machining Cost?

No two machining jobs are ever easy to compare for cost, but a few guiding principles can be applied in general. For example, for smaller batches, Swiss machining will always be more expensive than more traditional methods. This is a result of greater setup and programming/operational complexity. For higher-precision applications, Swiss machining is ideally suited to producing better precision and repeatability in parts, making it the only choice, so cost comparisons are redundant. For high precision and larger production volumes, Swiss machining is highly cost-competitive. 

Is Swiss Machining Expensive Compared to CNC Machining?

It depends. For identical parts produced by more normal CNC machining and Swiss machining, some comparisons are useful. For comparable precision, CNC machining generally requires a considerably longer per-part processing time than Swiss machining. This is a result of the need for very low cut depths for higher tolerance in CNC processing. In setup terms, the two processes are relatively cost-comparable. However, Swiss machining carries extra setup/programming costs in the operation of multiple cuts at the same time, which reduces per-part processing times. For high-volume production of high-precision small parts, Swiss machining is highly competitive with CNC machining.

To learn more, see our guide on Production CNC Machining.

What Is the Difference Between Swiss Machining and CNC Machining?

The differentials between the processes depend heavily on the nature of the CNC process being referenced. Swiss machining involves the following:

1. Close support by a sliding bushing at the cut point.
2. Part rotation and stationary rotational axis for different tasks.
3. Multiple cooperating cut points by several cutters, both point application and rotating.
4. Full auto-feed of bar stock to produce multiple parts in sequence from a single material billet/bar.
5. Swiss machines generally have less than 10 cutters set up and ready to present to the workpiece in a setup.

Overall, the difference between Swiss machining and the most advanced CNC machining centers is becoming blurred, as CNC capabilities continuously grow more intricate and advanced. CNC machining involves:

1. In 3-axis CNC machining, the part is held stationary and the rotating cutter moves.
2. In 4+ axis CNC machining the part can be rotated, either for positioning or for lathe-style cutting operations as required.
3. No localized support is presented to resist the application of forces by the cutter. This introduces the possibility of distorting the part or the position of the part during cutting operations and requires careful programming to avoid.
4. No automated material feed is generally included in CNC machines.
5. It is common for CNC machines to have up to 30–40 individual cutters racked and set up ready to change.

Summary

This article presented swiss machining, explained it, and discussed how it works and its various applications. To learn more about swiss machining, contact a Xometry representative.

Xometry provides a wide range of manufacturing capabilities, including machining and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.

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