Selecting a Material-Removal Process
Screen candidates by material, feature access, thickness and surface requirements before comparing production cost.
Screen the material and feature before choosing a machine; Checklist
Screen the material and feature before choosing a machine
- Identify the material, its condition and conductivity. Check Material Families and Material Properties.
- Mark the feature: through profile, blind cavity, shallow recess or finished surface. Identify tool access and any start-hole requirement.
- Record thickness, minimum internal radius and the thinnest remaining feature.
- Read the drawing's dimensional and surface requirements. Decide whether a thermal HAZ or recast layer is acceptable.
- Shortlist processes, then check actual equipment capability, finishing needs and production quantity.
Hardness alone does not select a process. A hard nonconductive ceramic rules out ordinary EDM even though EDM can cut hardened steel. See Tolerances and Fits and Surface Texture and Finish for what the finished part must meet.
Use the feature to narrow the candidates
Use the feature to narrow the candidates
| Part requirement | Candidate and reason | Check next |
|---|---|---|
| Hardened steel die with a through opening and small inside radii | Wire EDM: conductive work, low cutting force, fine profile | Wire radius plus gap, threading access and surface integrity |
| Blind cavity in hardened conductive metal | Sinker EDM: shaped electrode reaches a cavity | Electrode manufacture, wear and flushing access |
| Thick non-tempered glass plate with a through profile | Abrasive waterjet: no conductivity requirement or thermal HAZ | Glass type, thickness capability, piercing and edge quality |
| Shaped hole in a hard nonconductive ceramic | Ultrasonic Machining: abrasive impact removes brittle material | Tool wear, depth, chipping and required finish |
| Fine profile in thin metal sheet | Laser: concentrated beam and narrow kerf | Material match, HAZ and edge quality |
| Conductive metal plate blank for later machining | Plasma: productive thermal cutting candidate | Thickness capability and machining allowance |
| Soft foam gasket | Pure waterjet: water alone can separate soft material | Support, water compatibility and detail size |
| Repeated complex metal contours without an EDM recast layer | ECM: dissolution instead of melting | Material chemistry, electrolyte flow and tooling cost |
| Many shallow areas in metal sheet | Chemical milling: masked areas can be etched together | Undercut, depth control and surface finish |
Keep conventional machining on the candidate list; Practice
Keep conventional machining on the candidate list
For an accessible flat face, hole or round shaft in a machinable material, conventional cutting may be the simplest route. Use the family map to reach those methods. A part may combine sawing, milling and grinding, or use waterjet for a blank followed by machining of critical faces.
Increasing thickness can increase cutting time, taper or flushing difficulty. A thin remaining wall may deflect or be damaged even when cutting forces are small. Ask for evidence of capability on the actual material and geometry rather than relying on a universal tolerance ranking.
Practice selecting a process Practice HAZ reasoning
Safety references: Equipment Operating Procedure, Machine Hazards and Housekeeping and Chemicals and Safety Data Sheets.