Cementing & Fastening

Safety Concerns

Cementing Plaskolite acrylic sheet must begin with well machined parts. A square flush fit, without using excessive force, is required to produce a strong, attractive joint and to minimize the chance of "blushing". Cementing should be performed at room temperature in a well ventilated area. A low humidity environment will prevent cloudy joints. Parts to be bonded should not be flame or buff polished.

Types of Cements

Solvent cements - Water thin solvents that soften the acrylic, diffuses and evaporates, allowing the parts to harden together.

Mixed solvent cements - Solvent cement thickened with an acrylic polymer to slow cure times, and fill small voids.

Polymerizable cements - Methyl methacrylate monomer and a catalyst mixed to produce a cement for strong, long lasting museum quality joints.

Capillary Cementing

This technique allows solvent cement to flow into the joint and melt the parts together.

Apply cement with a syringe, solvent applicator, or eyedropper. Use small weights, fixtures, and fences to hold the parts in place (See Fig. 14). Initial bonding occurs within 5-10 seconds. A three hour cure time is sufficient to allow further fabrication, and 24-48 hours for maximum bond strength.

Dip/Soak Cementing

Place small wire brads in a level, shallow tray, pour in solvent to cover the brads. Rest the edge of acrylic on the brads for 1-5 minutes, depending on thickness, allowing the material to soften. Remove the acrylic, drain excess solvent, then quickly and precisely place the edge onto the other part. Hold the parts in place with fixtures or light weights, being careful not to apply pressure. After initial bonding occurs (30 seconds), steady slight pressure can be applied to remove any air bubbles. Allow the joint to cure for 5-20 minutes before moving, and 8-24 hours before conducting further machining or finishing.

Adhering To Other Materials

Care must be taken when attaching Plaskolite acrylic sheet to other substrates. Different coefficients of thermal expansion exist between the two pieces to be fastened, placing large stresses on the bond. To overcome the inherent stress along the joint, keep the dimension of the adhesive area as small as possible, and use elastic cements that remain flexible, such as caulks, polysulfides and rubber based adhesives. Pressure sensitive, double-faced tape, depending on the end use, may also be suitable for joining acrylic to other materials.

Mechanical Fastening

Attaching Plaskolite acrylic sheet to itself or to other substrates can be accomplished with screws, nuts and bolts, rivets, or other mechanical fasteners. However, when the acrylic is exposed to fluctuating temperatures, allowances for expansion and contraction must be provided. Drilling oversized holes or slots, using washers and spacers, and not overtightening the fasteners, will allow the acrylic sheet to move.

Ultrasonic Welding

Sonic welding: the use of electrical energy that is converted to mechanical vibration to melt acrylic sheet, can be used to press parts together.