Precision Bored Bushings

What drives the price of this part

Derived from the callouts on this page. Where a driver is not on the drawing, it is not on this list.

Tolerance

Bore tolerance at H7 (in place) is the tightest callout this family carries. Tightening a callout is a process decision, not a machining decision: below the standard ±0.005 mm the work moves to grinding or jig boring, and the price moves with it.

Part size

Bore range at Ø10–Ø300 mm decides which machine the part lands on and how many setups it needs. Size is the driver buyers most often leave out of a first enquiry, and it is the one that changes the quote fastest.

Surface finish

Surface roughness at Ra 0.4 µm. Every step below the ordinary as-machined Ra 1.6 µm adds a finishing pass; a callout on a face nobody touches is the most common over-specification we quote.

Material

The first material listed, Carbon Steel 4140 (42CrMo4), rates 6/10 on our machinability scale at 197–235 HB annealed · 28–32 HRC quenched and tempered. On this shop's scale a harder alloy means slower passes and more tool changes, and that is cycle time the quote has to carry.

Order size

Minimum order is 10 pieces, so on a first order setup and programming are spread over very few parts and they are most of the price. Repeat orders at the same quantity are cheaper without anything on the drawing changing.

See how cycle time is calculated in the machining time calculator and what else moves a price in the cost driver reference.

How these parts are inspected

Matched to the callouts above and the instruments actually on the floor.

• Coordinate measuring machine (Zeiss CONTURA G2, two machines, GR&R 8.4% on the critical feature)
• Dimensional report against the drawing, with a 100% check on critical features rather than a sample
• Certificate of conformance and the mill certificate with every shipment
• Surface roughness tester (Mitutoyo) against the Ra callout
• Bore gauges and an optical comparator for hole position and edge form

The full equipment list, with counts, is on the capability page; the inspection sequence is on quality and inspection.