Despite the name, screw machine parts are not limited to screws or fasteners. They are custom precision components machined from bar stock according to an OEM’s drawing and specifications.
Common examples include pins, shafts, bushings, spacers, fittings, inserts, couplings and valve components. Screw machining is often used for recurring production programs that require consistent dimensions and reliable part-to-part repeatability.
What Is a Screw Machine Part?
A screw machine part is produced by rotating bar stock while cutting tools create the required shape and features.
Depending on the equipment and part design, the process may include:
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- Turning and facing
- Drilling, boring and reaming
- Internal or external threading
- Cross-drilling
- Milling and slotting
- Grooving, knurling and cutoff
Mechanical multi-spindle, CNC multi-spindle and Swiss CNC machines can all produce screw-machined components. The right process depends on part size, geometry, tolerances, material and production volume.
Common Types of Screw Machine Parts
Pins, Shafts and Spacers – Pins, shafts and spacers are used to locate, connect, guide or separate parts within an assembly.
These components may include stepped diameters, grooves, threads, cross holes, flats or chamfers. Important requirements can include straightness, concentricity, surface finish and press-fit dimensions.
Bushings and Sleeves – Bushings and sleeves help control movement, maintain alignment or provide a wear surface.
Key specifications often include inside and outside diameter, wall thickness, bore finish and concentricity. Because these parts usually mate with another component, small dimensional changes can affect fit and performance.
Fittings, Adapters and Hose Components – Precision-machined fittings are commonly used in hydraulic, pneumatic, plumbing and fluid-control systems.
Examples include adapters, couplings, ferrules, hose ends, compression nuts and unions. These parts may require threaded connections, internal passages, sealing surfaces, wrench flats or intersecting holes.
Inserts and Threaded Components – Threaded inserts, molded inserts, standoffs, studs and custom threaded pins are used in industrial, electrical and molded-product assemblies.
They may include internal or external threads, knurls, barbs or grooves. The drawing should clearly identify thread size, pitch, class of fit and mating-part requirements.
Valve and Fluid-Control Parts – Valve stems, spools, nozzles and similar components may include precision bores, grooves, sealing diameters, threads and cross holes.
Their performance often depends on controlling both individual dimensions and the relationship between multiple features.
What Makes a Part a Good Fit for Screw Machining?
A part may be a good candidate when it:
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- Can be produced from round, hexagonal or shaped bar stock
- Has primarily cylindrical or turned features
- Requires multiple operations that can be completed efficiently
- Will be ordered in recurring production quantities
- Requires consistent inspection across each release
Multi-spindle machining is often economical for medium- to high-volume parts with repeatable features. Swiss CNC machining may be better for slender, small-diameter or more intricate components.
Avanti Engineering focuses on recurring production programs, typically beginning at approximately 1,000 pieces. The drawing, annual usage and release quantities should be reviewed before selecting a process.
Materials and Design Considerations
Screw-machined parts can be produced from materials such as:
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- Carbon, alloy and stainless steels
- Aluminum
- Brass, bronze and copper
- Engineered plastics
- Phenolic and composite materials
Material selection should reflect the part’s strength, corrosion resistance, weight, conductivity, wear and operating environment.
Manufacturability can also be affected by tight tolerances, deep holes, thin walls, long unsupported sections, surface-finish requirements, cross holes and milled features.
Tolerances should match the part’s function. Unnecessarily tight dimensions can increase tooling, inspection and production costs without improving performance.
Secondary Operations and Quality Requirements
Some parts require additional operations after machining, including grinding, broaching, slotting, heat treating, plating, washing or light assembly.
For recurring OEM programs, quality requirements should be identified during quoting. Avanti supports production through its ISO 9001:2015-certified quality system, including SPC, C=0 acceptance sampling, NIST-traceable measuring equipment, first-article inspection, ISIR and PPAP support, and material and process traceability.
What Should Be Included in an RFQ?
Providing complete information helps the manufacturer select the right equipment and prepare an accurate quote. Include:
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- Current drawing and revision
- Material grade and condition
- Annual usage and release quantities
- Critical dimensions and tolerances
- Surface-finish requirements
- Secondary operations
- Inspection and documentation requirements
- Packaging and delivery expectations
The print should also identify dimensions that are critical to fit, sealing, movement or final assembly.
Request a Quote for Custom Screw Machine Parts
Avanti Engineering has manufactured custom screw machine products and precision-turned components since 1972. Capabilities include mechanical and CNC multi-spindle machining, Swiss CNC machining, CNC turning, in-house tooling and secondary operations.
Send Avanti your drawing, material specifications, annual usage, release quantities and quality requirements for review.
Call 630-260-1333 or request a quote online to discuss your recurring production program.
Frequently Asked Questions
Are screw machine parts the same as machine screws?
No. A machine screw is a specific type of threaded fastener. A screw machine part can be any custom component produced on screw machining equipment, including pins, shafts, bushings, fittings and inserts.
Why are they called screw machine parts?
The term comes from automatic machines originally developed to produce screws and threaded products. Modern screw machines produce a much broader range of custom precision components.
What is the difference between screw machining and CNC turning?
Both processes remove material from rotating stock. Screw machining usually refers to automated bar-fed production using multi-spindle or Swiss-type equipment. Conventional CNC turning may be more suitable for lower volumes or frequently changing parts.
Is screw machining only for high-volume production?
It is generally most economical for recurring production because setup and tooling costs can be spread across larger quantities. The right volume depends on the part, material and release schedule.
Can screw-machined parts include secondary operations?
Yes. Parts may require grinding, broaching, heat treating, plating, cleaning or light assembly after machining.