Assembly and Tryout
Assembly and tryout is where the tool proves itself in the press or molding machine. The exam tests fitting practice, alignment and doweling, press-fit calculations, die setting, first-off inspection, and the documentation that closes out a tryout.
Fitting and alignment
Blue the mating surfaces and check bearing: contact should be even, and 75–80% bearing is acceptable for most die components. Scrape or grind high spots rather than forcing the fit. Align first, then dowel; dowels locate and bolts clamp. Torque bolts in a crossing sequence, in stages, to avoid distorting a plate.
Press fits and keys
Interference fits are assembled by pressing or by heating the outer part. Thermal expansion Δ = α × L × ΔT; for steel α ≈ 11.5 µm/m per °C. Keys transmit torque and must fit the keyway on the sides, with clearance on top.
Die setting and tryout
Verify shut height against the press specification, set the ram adjustment, and use die safety blocks any time hands enter the die area. Check the feed line, piloting, and strip lift before cycling under power. Run slowly at first, watching for slug pulling, galling, and unusual noise. Tryout is also when press tonnage is confirmed against the calculated cutting and forming load.
First-off inspection
Measure the first parts completely, not just the critical feature. Record dimensions, adjust stops, and decide whether variation comes from the tool or the process. A dimension 0.05 mm off is corrected by adjusting the tool, not by accepting it.
Worked example
A Ø50 mm bearing must be installed in a steel housing with 0.05 mm diametral interference. Heating the housing 150 °C above ambient expands the bore by 11.5 × 10⁻⁶ × 50 × 150 = 0.086 mm - enough to slide the bearing in, provided the bearing stays at ambient. Reasoning: expansion applies to the diameter as well as the length; check interference plus assembly clearance against the calculated growth.
Traps
Bolting before doweling; torqueing in a circle rather than a crossing pattern; entering the die area without a safety block; and adjusting the ram to compensate for a tool that is machining incorrectly.