Low-volume custom fastener sourcing: a practical RFQ checklist

1. Decide whether the part is truly custom

Before requesting a custom quote, compare the design with a standard fastener catalogue. A standard bolt, nut or washer can usually be purchased faster and at a lower cost. Custom production is more useful when dimensions, material, thread, finish or an assembly interface do not fit a catalogue item.

Common custom or special items include mixed-thread studs, long bolts, non-standard heads, spacers, locating pins, bushes, adapters, security fasteners and parts that must match an existing housing or mating component.

2. Prepare one drawing package

Send the same revision-controlled drawing to every supplier. Avoid sending several conflicting PDFs, an unmarked photo or a sketch without units. The package should include:

• The latest drawing revision with a revision date or number.
• All dimensions, tolerances, thread specification and units.
• Material grade and an acceptable equivalent, where applicable.
• Heat treatment, surface finish, plating or passivation requirements.
• Critical characteristics and the inspection method or report needed.
• Expected annual use, trial quantity and minimum order quantity.
• Packaging, labelling and delivery destination.
• Any assembly context that affects orientation or function.

3. Define the thread and material precisely

Thread calls such as “M8” are incomplete for custom work. State the thread standard, pitch and direction, for example M8 x 1.25, UNC, UNF, BSPP or NPT. If a thread must fit an existing assembly, include the mating part drawing or a verified go/no-go gauge requirement.

For stainless steel, distinguish between grades and properties that matter for the application, such as 303, 304, 316, A2 or A4. For brass, copper and carbon steel, state the grade if it affects strength, corrosion resistance, electrical performance or finishing. Do not use “stainless” alone when the application has a specific corrosion risk.

4. Separate functional tolerances from general tolerances

Not every dimension needs the same tolerance. Identify the dimensions that affect fit, sealing, concentricity, fatigue or assembly. A clear general tolerance block plus marked critical dimensions is more useful than tightening every tolerance and increasing cost without a functional reason.

If a dimension cannot be measured with a standard caliper, state the inspection method or provide an inspection fixture requirement. This is especially important for long parts, threads, tapers, runout and position tolerance.

5. Set a trial quantity and a realistic forecast

A quote for 20 pieces, 200 pieces and 1,000 pieces can use different processes. Ask for a transparent price break rather than a single number. Explain whether the first order is a sample, a repair batch, a pilot build or recurring production.

A supplier should state whether tooling, programming, custom gauges or setup charges are included. It should also explain whether those costs repeat on the next order and whether the quoted process remains suitable after the annual volume is confirmed.

6. Ask for a manufacturability review before price only

A useful RFQ response identifies questions as well as a price. The supplier should flag ambiguous dimensions, unavailable material, unachievable tolerances, finishing risks and inspection gaps. This review is most valuable before a sample is made.

7. Compare more than unit price

Compare the material certificate, process route, inspection plan, packaging, freight basis and replacement policy for nonconforming parts. Ask whether the quoted price is for the exact drawing revision and quantity shown.

For a first trial, a clear nonconformance and replacement process can be more important than a small difference in piece price. Keep the approved sample, drawing revision and inspection record connected to the purchase order.

8. Use a concise RFQ message

A short first message can be more effective than a long catalogue request. A practical example is:

We need a quotation for the attached fastener drawing, revision B. Material is 316 stainless steel, finish is passivated, and the trial quantity is 250 pieces. Please identify any dimensions that need clarification and confirm whether you can provide a material certificate and dimensional inspection report. The delivery destination is the United Kingdom.

Safety and application scope

Fasteners used in safety-critical automotive, medical, aerospace, pressure-vessel or lifting applications require qualification, traceability and inspection controls beyond a general commercial RFQ. Do not assume that a supplier is qualified for those applications only because it can machine a similar-looking part.