Initially,
Plastic Media Blasting (PMB)was restricted to the aircraft
and aerospace industries. Through many years of operation
and technology refinement, it was found that PMB was very applicable to
other industries. The applications of PMB are only limited by the imagination
of the operator, given the multitude of applications discovered each year.
Sibley Engineering, Inc (SEI) provides PMB services in two main areas;
industrial and commercial/private.
SEI
has recognized a need in the plastics industry for an effective and economical
way to clean molds. The molds used to produce plastic parts develop a
buildup of residue from mold releases, lubricating agents, burnt polymers
and cooling liquids. This residue needs to be cleaned periodically to
maintain cosmetic and dimensional requirements. Traditionally, sandblasting
cannot be used for cleaning finished molds due to its ability to etch
the surface and actually remove metal. Typically, this is accomplished
using questionable chemicals and hand or mechanical scrubbing by available
employees. This method presents a health hazard, is environmentally unsafe
and the true costs vary based on the hourly rate of available labor. If
low cost unskilled labor is not available, a highly compensated machine
operator or machinist must be used which could effectively double or triple
the cost of these necessary cleaning operations. SEI will provide a fast,
safe, professional cleaning service at a known and consistent cost.
The
automotive and refinishing can also
extensively utilize PMB. PMB is an effective and economical process to
strip finishes from thin gauge automobile body panels. It does not harm
or distort the metal as sandblasting does. The process yields a smooth,
ready-to-paint surface. Chemical paint stripping is an environmentally
unsafe health hazard and yields a semi-liquid waste residue that is difficult
to dispose of. Hand or mechanical sanding is very labor intensive, and
therefore costly. Extensive scraping and grinding can further damage the
metal surface requiring additional bodywork and more sanding. Restoration
businesses and body shops acknowledge the advantages of PMB paint stripping.
SEI will provide a fast, professional paint stripping service to accommodate
the commercial/private needs of its customers.

The Process
PMB is a dry abrasive blasting process designed to replace chemical paint
stripping operations and conventional sandblasting. It is performed in
a ventilated enclosure. PMB is similar to conventional sandblasting except
that soft, angular plastic particles are used as the blasting medium.
The PMB process propels the plastic media at a much lower pressure (less
than 40 psi) than conventional blasting. PMB is well suited for stripping
paints, since the low pressure and relatively soft plastic medium have
minimal effect on the surfaces under the paint.
Plastic
media are manufactured in a variety of type, sizes, and hardness. A military
specification (MIL-P-85891) has been developed for plastic media. The
specification provides general information on the types and characteristics
of plastic media.
The
7 types of media are:
- Type I - Polyester (Thermoset)
- Type II - Urea formaldehyde (Thermoset)
- Type III - Melamine formaldehyde (Thermoset
- Type IV - Phenol formaldehyde (Thermoset)
- Type V - Acrylic (Thermoplastic)
- TyepVI - Poly (allyl diglycol carbonate0 (Thermoset)
- TypeVII - Starch-g-acrylic