Innovations In High Performance Cryogenic Deflashing Compounds

Technical advances in the design of cryogenic shotblasting equipment have enabled the process of deflashing complex, precision rubber mouldings to be carried out with consistent and reliable results. Increased thermal insulation, accurate blasting parameters and a more efficient distribution of blast media have all contributed to reduced costs, higher quality and improved throughput speeds.

One area of the deflashing process that has failed to keep pace with these developments is the continued use of polycarbonate resins as the blasting media despite the considerable advances in polymer engineering over this period. At room temperature polycarbonate resin is a tough, resilient material with good impact strength and a high resistance to surface abrasion. However once the temperature falls to sub zero levels, the polymer becomes brittle and starts to breakdown into dust, reducing the shotblasting efficiency.

Once the temperature reaches -30°C the blast media has lost almost 70% of its original impact strength and this rapid deterioration in mechanical properties continue to -80°C when the polymer structure can fail completely.

While the addition of plasticizers can overcome many of these problems, the resulting blast media is soft and inefficient with poor abrasion resistance and low kinetic energy.

These inefficiencies in the deflashing process require excessive use of blast media, liquid nitrogen consumption and blasting wheel speeds to compensate for this poor performance.

Recent innovations in molecular engineering have enabled base polycarbonate resins to be crosslinked with various fluoro polymers that withstand the challenging conditions demanded in high performance cryogenic shotblast applications and equipment. Increased performance greater efficiencies and reduced cost combine with improvements in quality standards exceeding those found in standard blast compounds.

DIEBLAST GREEN

A polycarbonate / PTFE co-polymer with low temperature mechanical properties exceeding standard cryogenic grade blast media.

View details of the DIEBLAST GREEN cryogenic blast media

DIEBLAST CRYSTAL

Branched molecular structure prime polycarbonate, fully crosslinked to produce a tough, durable blast media with maximum efficiency and lon life.

View details of the DIEBLAST CRYSTAL cryogenic blast media

Cubic Engineering

Standard polycarbonate shotblast media is normally manufactured in the form of cylindrical granulate 30th diam (0.75mm) being the most common size for the deflashing precision mouldings.

In depth analysis of deflashing results show that cubic granulate are more efficient throughout the blasting process. The addition of extra corners and cutting edges enhances performance while the mass and kinetic energy produced by each particle is increased by up to 27%.

With both DIEBLAST grades retaining their size and shape longer than standard blast media this greater efficiency is maintained throughout the blasting cycle down to -120°C.

27% Greater Kinetic Energy

Breakdown rates in blast media either by surface erosion or fatigue failure have more dramatic and adverse affects on the efficiencies in cryogenic applications than conventional room temperature blast systems.

A 10% erosion on the surface of standard 45tho (1mm) granulate, reduces the kinetic energy by almost 50%.

Operating at only half its efficiency, the blasting process requires lower temperatures, increased wheel speeds or extended cycle times to compensate for this loss in performance.

These changes in blast parameters lead to even higher media consumption and the production of “expensive dust”.