Plungers, segments, push rods, extenders, siphons, rings

Omnia Press produces and repairs the spare parts for zinc and magnesium alloys with numeric-controlled machines, using quenched and tempered steels and sometimes with special steels. The plungers, segments, push rods, extenders and the external structure of the siphons are made of X37CrMoV51KU, while the shot-sleeves are made of X40CrMoV511KU.

The plungers can be made of cast iron according to the producer original designs (the cast iron type depends on the producing company), final treatment is a 36-hour gaseous nitriding.
As for the shot-sleeve, the mechanical processing starts from the tailor-cut round bars; the hole is performed on vertical machines, the processing on numeric-controlled parallel lathes and the milling on machine tools; final grinding is performed on numeric-controlled machines. The piece is then hardened and tempered as follows:

1. Preheating process at 650°C;
2. 2-hour preheating process at 830°C;
3. 2-hour vacuum austenitizing treatment at 1020°C
4. Cooling in thermal baths at 500°C and 200°C

According to the desired hardness value, it is possible to perform three tempering treatments:

1. Tempering at 560-620°C;
2. Tempering at 560 -620°C;
3. Tempering at 560-600°C;

The external mechanical finishing is performed with universal numeric-controlled grinding machines, while the holes are finished with vertical smoothing mills, which grant centesimal tolerances:

• Hole lapping up to Ra 0.2;
• Hole tolerance H6; round hole max. 0.02 mm.;
• Orthogonality max. 0.02 mm.; Coaxiality max. 0.02 mm.;
• Parallelism max. 0.02 mm.;

After grinding, a dimension control certificate is released. The shot-sleeve is placed into the preheated siphon according to a procedure called "hot insertion".