Swiss screw machine parts are usually bought in quantity: pins, contacts, small shafts and sleeves that repeat across thousands of assemblies. That makes the quote more sensitive to what is missing from the enquiry than to the unit price on the first line. This guide explains what drives the price of a Swiss-turned part, why quantity changes it, and which details let a supplier quote the part you will actually accept.
A useful quote for Swiss screw machine parts is built from the complete delivered requirement: drawing revision, material grade and condition, finish, critical dimensions with their inspection method, and sample, first-batch and annual quantities stated separately. Missing any one of them turns the price into an assumption.
01
What counts as a Swiss screw machine part?
In North American purchasing, “screw machine parts” or “screw machine products” describes small turned components made from bar stock in volume. Today most of that work runs on CNC Swiss-type, or sliding-headstock, lathes. The guide bush supports the bar close to the tool, so slender features can be turned without the part deflecting under cutting force.
Typical examples are guide pins, contact pins, spring-probe plungers and barrels, fiber ferrule holders and sleeves, small shafts and threaded inserts. These are part types OUJI has made. What they share is a small diameter, several features that must stay concentric, and demand measured in thousands of pieces rather than tens.
If you are still deciding whether a part should go Swiss at all, start with Swiss screw machining vs CNC turning. This article assumes the process is chosen and focuses on getting a comparable quote.
02
What drives the price of a Swiss-turned part
Swiss-type production front-loads its effort. Programming, tooling and proving the first good part happen once per setup. After that the machine runs from the bar feeder, and the cost of each piece is driven mainly by cycle time rather than by handling. Anything that lengthens the cycle or adds a step outside the machine shows up in the unit price.
Live tooling and back-spindle work let cross holes, flats, slots and back-side features be finished in the same setup. That usually beats a second operation, but every added feature still adds seconds to every part. When two quotes differ widely, ask each supplier which features drive the cycle and which steps happen off the machine.
- Setup and program proving, shared across the batch
- Cycle time, set by the number and difficulty of features
- Bar stock grade, diameter and condition, plus material lost to the cut-off
- Secondary steps such as plating, heat treatment, deburring or cleaning
- Inspection frequency, measurement method and reporting
- Handling and packaging that protect small parts and keep counts accurate
03
Why quantity changes the quote
Because setup is shared across the batch, the same part can carry a very different unit price at 100 pieces and at 10,000. At OUJI, Swiss machining samples start at 100 pieces and production batches start at 1,000 pieces. Give the sample quantity, the first production batch and the expected annual volume as three separate numbers.
An annual forecast is planning information, not a commitment. It still helps the supplier decide which machine to dedicate, how much bar stock to plan and whether to keep the setup for repeat orders. A supplier who knows the part will repeat can retain the program and approved first article instead of starting over each time.
For scale, the published C3604 brass case covers a 200,000-part project with threads, knurling and stepped diameters. Your own quantity does not need to be that large to justify Swiss production.
04
What to send with the RFQ
Most re-quotes and delays come from details the first enquiry left open. Use the checklist below so that every supplier quotes the same delivered part.
| Send this | Why it changes the quote |
|---|---|
| Dimensioned drawing with revision, plus a 3D model if available | Defines every feature the cycle must produce and which revision is being quoted |
| Material grade and condition, with any approved substitutes | Sets bar stock cost and availability, and how the material machines |
| Sample quantity, first batch and annual volume | Determines how setup cost is shared and which machine is planned |
| Finish or plating, and which dimensions apply after finishing | Adds an outside process and changes the machining allowance |
| Critical dimensions, datums and the required report format | Sets inspection time, method and sampling frequency |
| Burr-sensitive edges, contact areas and handling or packaging needs | Small parts are easily damaged or mixed; protection adds steps |
If a requirement is still open, say so. A supplier can quote options, but only if it knows which decision is pending.
05
Make the drawing do the explaining
Mark the functional interfaces: the locating diameter, sliding surface, mating bore or contact area. Tight limits on those features are expected; tight limits on everything make the part slower to machine and inspect without improving how it works. If a feature is meant to flex or is lightly supported in the assembly, explain its function.
Name the material grade and condition rather than the family. “Brass” or “stainless” leaves room for different quotes on different stock. The materials for Swiss screw machining guide covers what to specify for brass, stainless steel, BeCu C17200, Kovar and phosphor bronze.
For plated parts, state which dimensions are accepted after plating and which surfaces must stay uncoated. Gold over nickel plating is available at OUJI; the required finish and thickness should be written into the enquiry, not left to a later email.
06
Agree inspection before the first batch
On small parts, the measurement method matters as much as the tolerance. Hand gauges can deform a slender pin or fail to reach a small feature. OUJI uses KEYENCE optical measurement for features of this size. Identify which dimensions need to be reported and in what format, so the method is agreed before quoting.
Decide how the first article is approved and how production is checked afterwards. On the C3604 brass project, key dimensions and internal thread depth were sampled every 30 minutes during production. That interval belongs to that project; your sampling plan should follow the risk of your own features.
07
Send your Swiss screw machine part for review
OUJI’s Swiss-type lineup covers parts up to a standard Ø32 mm machining diameter, with a focus on parts under Ø10 mm. The smallest diameter we have produced to date is Ø0.3 mm. Feasibility for very small features depends on length, material and geometry, so it is confirmed against the drawing rather than promised in advance.
Review the Swiss screw machining service, then send your drawing, material and quantities. OUJI responds within 1 day with next steps, clarification questions or quotation details. The photographed Swiss machining process shows how parts move from bar stock through machining and optical inspection.
Sources & technical references
- OUJI Swiss screw machining capability and enquiry requirements — OUJI
Source for the sample and production batch quantities, maximum machining diameter, part types, plating and measurement statements.
- C3604 brass production case — OUJI
Project-specific source for the 200,000-part quantity and 30-minute sampling interval.
- Swiss-type CNC automatic lathe: guide-bush and sliding-headstock explanation — Star Micronics
Manufacturer reference for the guide-bush support principle summarized in the first section.
