Spray Up Method / Open Mold
Spray-up or chopping is an open mold method similar to hand lay-up in its appropriate for making boats, tanks, transportation components and tub/shower units in a large variety of shapes and sizes. A chopped laminate has good conformability and is sometimes faster than hand lay-up in molding complex shapes. In the spray-up process the operator controls thickness and consistency, therefore the process is more operator dependent than hand lay-up. Although production volume per mold is low, it is feasible to produce substantial production quantities using multiple molds. A skilled operator is required to ensure correct application of glass to mould. The spray up laminate is then consolidated by hand to achieve a homogeneous laminated surface. Several layers of chopped material or specialised reinforcements can be added to the laminate depending upon the requirements of the application.
Process
As in hand lay-up, gel coat is first applied to the mold prior to spray-up of the substrate laminate. Continuous strand glass roving and catalysed resin are fed through a chopper gun, which deposits the resin-saturated “chop” on the mold. The laminate is then rolled to thoroughly saturate the glass strands and compact the chop. Additional layers of chop laminate are added as required for thickness. Roll stock reinforcements, such as woven roving or knitted fabrics, can be used in conjunction with the chopped laminates. Core materials of the same variety as used in hand lay-up are easily incorporated.
Other benefits of the spray up process include:
- Simple, low-cost tooling.
- Portable equipment permits on-site fabrication.
- Virtually no part size boundaries.
- The process may be automated.
- Process flexibility
- Low tooling costs
- Lower cost than hand lay-up
- Lower resin to glass ratio can be achieved giving stronger parts
- Speed of laminating is increased so parts can be demoulded quicker 3-4 times per shift (100 – 200 parts per month)
- Ideal process for the production of low-to-medium volume parts
Advantages
Spray up moulding is very effective in the production of complex shapes and there are virtually no restrictions on the size of part that can be produced.
Applications
Prazastinav produces a wide variety of parts using the spray up process for the following industries:
- Automotive and trucking industry
- Public transportation
- Industrial and manufacturing
