Dip molding, the second oldest profession, had its origin in candle making. After the second world war, plastisol
came on the market for non-military use. Plastisol dippings immediately became the standard for tool handles.
It still is.
Piper was founded in 1958 as a chemical company supplying a range of coating materials to
the rapidly growing plastic coating industry. Piper did its first dip molding job in 1959.
The cost of molding by dipping is always low. Most molds are very simple and inexpensive.
Dip molding, if automated is competitive with any other molding process.
Plastisol is a vinyl compound that is liquid at room temperature and will keep for
years. When heated it fuses into ordinary vinyl never to liquefy again. Plastisols can be compounded to
produce vinyl’s in almost any durometer (hardness), clarity and color and properties like electrical,
chemical, and weathering. Surface appearance can go from shiny to matte. It can also be compounded to
meet many standards, including FDA food contact, Non-Toxic,
USP Class VI
, UL, & MIL-P-20689.
Plastisol dip molding is a thermal process. Metal molds are preheated, dipped, and then post heated. During the dip, heat in the molds gels the surrounding material. The hotter the mold and the longer the dip, the thicker the gelled coating. During the "cure", the plastisol fuses. Naturally, temperatures and dipping profiles are critical in determining the amount of plastisol buildup on the part. Its amazing the shape of parts that can be made by dipping. Since they are elastic, complex parts can easily be stripped from molds.
The parts made by dip molding are precision. Plastisol follows
the detail of the mold exactly. The inside of the part is an exact negative of the mold. It even has the same
surface texture, (shiny or matte) that the mold has. The outside dimensions of the parts are surprisingly controllable.
Wall thickness can be held to very close tolerances. Using precisely controlled ovens, dip speeds, dip times,
and withdraw speeds; a range of wall thickness configurations of is achievable.
Piper Plastics has developed machinery that is possibly the most
accurate in the world. Our equipment is both high precision and efficient. Our oven technology utilizes high
velocity forced air and PID control accurate to ±1°F at 450 degrees. Our dipping profiles are infinitely
adjustable with resolution and accuracy of .005” and 0.1”/minute in position and velocity respectively.
Piper’s technology results in lower costs because of low reject rates, fast setup time, and fast cycle
times associated with computer-controlled equipment.
Currently Piper operates 19 centrally networked dipping systems
in both industrial and clean room environments. We operate our systems 24 hours per day, and are adding capacity
on a constant basis.
Piper also compounds its own plastisols. Therefore we are very
responsive to special requirements of properties and colors.