Two Bushing Architectures

The fundamental choice in drill bushing selection is between a monolithic press-fit bushing (Type P) and a two-piece slip-renewable system (Type S in liner). Each optimizes for a different production scenario.

Head-to-Head Comparison

FactorFixed (Type P)Renewable (Type S)
InstallationPress-fit into jig plate (permanent)Slip into liner bushing (removable)
Accuracy±0.005 mm (direct press-fit)±0.008 mm (liner + bushing stack)
Tool Change TimeN/A — fixed bore<10 seconds
Unit Cost$8-15$15-25 (bushing) + $10-20 (liner)
Replacement CostMust remove press-fit bushingSlip out, replace, slip in
Multi-OperationOne bore size onlyMultiple bushings per liner

When Fixed Bushings Are Better

  • Single drill size per hole: The jig drills one size only — no need for tool changes at that location
  • Maximum accuracy required: Direct press-fit eliminates the liner-to-bushing clearance that adds ±0.003 mm error in renewable systems
  • High volume: Bushing replacement is rare enough (every 50K-100K holes) that press-out/press-in is acceptable
  • Budget constrained: Fixed bushings cost 40-50% less than a renewable system (bushing + liner)

When Renewable Bushings Are Better

  • Multi-operation holes: Same hole needs drilling → reaming → tapping, each requiring a different bushing bore
  • Frequent wear replacement: In abrasive materials (cast iron, composites), bushings wear quickly. Slip-out replacement takes seconds vs minutes for press-fit
  • Shared jigs: When the same jig serves multiple part numbers with different hole sizes at the same location

The Liner System

Renewable bushings require a liner bushing (Type HL) permanently pressed into the jig plate. The liner provides:

  • A standardized bore that accepts any slip bushing of the matching OD
  • A head flange that prevents the bushing from pushing through the plate under drilling force
  • A locking mechanism (typically a set screw or spring detent) that prevents the slip bushing from rotating