Adhesives Magazine

Pump it up

May 1, 2005
Pumps provide precision dispensing in hot-melt adhesive applications.

Caption; Zenith HPB pump provides uniformity and product stability.
Adhesives provide a low-cost, effective method for joining various substrates. Applied by a dispenser, spray nozzle or hand held gun, an adhesive joint offers better stress distribution, superior fatigue resistance, and greater strength over traditional bonding methods.

Challenge

The most common concern facing adhesive users is uneven spraying or dispensing. Reciprocating pumps, such as diaphragm or piston pumps, produce a flow that varies in both pressure and volume. To compensate, additional adhesive must be applied to sufficiently coat the target areas. Overspraying and overdispensing cause excessive material waste and increased manufacturing costs.

Other concerns when applying hot-melt adhesives are high viscosity, high operating temperature and pump accuracy. The viscosity of hot-melt adhesives is generally about 500 poise with operating temperatures ranging from 300°F to 400°F. Pump accuracy is critical when dispensing precise amounts of adhesive to a specified area.

Solution

The pump of choice for dispensing hot-melt adhesives is typically a positive-displacement gear pump. This high-precision pump must offer the capability of pumping high-viscosity fluids and be able to operate at high temperatures. Zenith offers precision metering pumps that provide pulseless metered flow to an applicator while generating the necessary pressure to meet system requirements.

Benefits of the pumps include the following.

Precise, consistent flow - A typical hot-melt adhesive machine includes a melter with the capacity for mounting one to four pumps. By installing a precision metering pump to each mount, the hot-melt adhesive can be accurately metered to the applicators. The result is a precise, smooth and consistent flow, which virtually eliminates costly overspraying, overdispensing, and wasted material.

Increased throughput - To increase throughput while minimizing operating, manufacturing and maintenance costs, a planetary metering pump can be mounted directly to the applicator and fed by a low-cost transfer pump. Up to 32 metered streams are available from a single pump, greatly increasing throughput.

Improved quality - Manufacturers and users of adhesive dispensing machinery can improve quality and reduce waste with the use of Zenith precision metering pumps. Throughput can be maximized while minimizing the size, complexity and maintenance of existing or new adhesive machinery.

For more information on pumps, contact Zenith Pumps at (800) 277-8968 or (919) 775-4600; or visit http://www.zenithpumps.com.