commercial fibreglass production
Production Methods
Fibreglass Developments Limited uses several methods of mould production in the factory. Each process has its own characteristics as well as limitations as to part size, shape, production rate, compatible reinforcements and suitable resin systems.
Fibreglass Developments Limited uses several methods of mould production in the factory. Each process has its own characteristics as well as limitations as to part size, shape, production rate, compatible reinforcements and suitable resin systems.
Open Moulding - THE BASIC SYSTEM
Hand Lay
The basic system where everyone starts - "Bucket and Brush". Used for low to medium volume production, the hand lay process provides only one finished surface. At FDL we use this method for production of children's rides.
The hand lay method involves placing the fibre reinforcement, in the form of chopped strand mat, into the mould and applying the catalysed resin by hand - usually from a bucket, using a brush. Other higher strength reinforcements can also be added this way. This method offers good control of materials, enabling control of thickness and resin to glass ratio.
Spray Up
Also used for low to medium volume production, spray moulding is used for similar products as hand lay, but allows for greater shape complexity. A chopper gun is used to deposit the chopped strand reinforcement and resin. This method is more operator dependant to get the desired result, but this is additionally monitored by the use of flow meters and scales for materials. Its advantage is that it is quicker and cheaper for production of large items, or large numbers. As size diminishes it becomes more wasteful due to overspray.
At FDL we use the above methods for production of many items including Breeze Bustas (truck air deflectors)
The basic system where everyone starts - "Bucket and Brush". Used for low to medium volume production, the hand lay process provides only one finished surface. At FDL we use this method for production of children's rides.
The hand lay method involves placing the fibre reinforcement, in the form of chopped strand mat, into the mould and applying the catalysed resin by hand - usually from a bucket, using a brush. Other higher strength reinforcements can also be added this way. This method offers good control of materials, enabling control of thickness and resin to glass ratio.
Spray Up
Also used for low to medium volume production, spray moulding is used for similar products as hand lay, but allows for greater shape complexity. A chopper gun is used to deposit the chopped strand reinforcement and resin. This method is more operator dependant to get the desired result, but this is additionally monitored by the use of flow meters and scales for materials. Its advantage is that it is quicker and cheaper for production of large items, or large numbers. As size diminishes it becomes more wasteful due to overspray.
At FDL we use the above methods for production of many items including Breeze Bustas (truck air deflectors)
Closed Moulding - More expensive processes to meet specific requirements & advantages
Resin Inject, RTM (Resin Transfer Moulding),
The resin injection method is used where high production rates or specific criteria such as critical wall thickness or two moulded faces are required. Reinforcement is placed in the bottom half of the mould. The mould is then closed and clamped, and catalysed resin is then pumped into the mould under pressure until the mould is filled. The process is more akin to plastic injection moulding stepped down a little. While injection pressures are a lot lower, still at 30-60 psi, multiplied over the entire mould surface, the load is tremendous, requiring very strong A & B (upper and lower) moulds, contributing to the expense.
A high production rate is possible if using a pigmented resin and a non-gel coated industrial surface is acceptable. Production rates drop dramatically if gelcoat is required. This method was used at FDL for production of the Post Office sorting trays project
RTM Light
A variation on the above, but using a lightweight B mould to save cost. The process is more akin to vacuum infusion rather than true RTM. The mould is prepared and loaded much the same as RTM, but there the similarity stops. The perimeter flange is held down by max vac, 1 bar, and the inner area, the B mould has 0.5 Bar vac applied. Resin is then fed in at 0 pressure, and the vac draws it into the mould. As the compression on the materials is somewhat less than RTM, these articles typically are more Resin rich than other processes.
If there are no specific criteria that demand closed moulding, then due to the expense and time required to make RTM moulds, it can often be more economical to make several open moulds to meet the production requirement and produce a cheaper article. RTM products require more expensive reinforcement, the resin pigment is an additional cost, there is considerable waste, and post moulding trimming is always required to remove the flash. Open moulded products can be trimmed to size in the moulds.
The resin injection method is used where high production rates or specific criteria such as critical wall thickness or two moulded faces are required. Reinforcement is placed in the bottom half of the mould. The mould is then closed and clamped, and catalysed resin is then pumped into the mould under pressure until the mould is filled. The process is more akin to plastic injection moulding stepped down a little. While injection pressures are a lot lower, still at 30-60 psi, multiplied over the entire mould surface, the load is tremendous, requiring very strong A & B (upper and lower) moulds, contributing to the expense.
A high production rate is possible if using a pigmented resin and a non-gel coated industrial surface is acceptable. Production rates drop dramatically if gelcoat is required. This method was used at FDL for production of the Post Office sorting trays project
RTM Light
A variation on the above, but using a lightweight B mould to save cost. The process is more akin to vacuum infusion rather than true RTM. The mould is prepared and loaded much the same as RTM, but there the similarity stops. The perimeter flange is held down by max vac, 1 bar, and the inner area, the B mould has 0.5 Bar vac applied. Resin is then fed in at 0 pressure, and the vac draws it into the mould. As the compression on the materials is somewhat less than RTM, these articles typically are more Resin rich than other processes.
If there are no specific criteria that demand closed moulding, then due to the expense and time required to make RTM moulds, it can often be more economical to make several open moulds to meet the production requirement and produce a cheaper article. RTM products require more expensive reinforcement, the resin pigment is an additional cost, there is considerable waste, and post moulding trimming is always required to remove the flash. Open moulded products can be trimmed to size in the moulds.
Vacuum Bagging - Several types, Hi performance laminates. Hi reinforcement to resin ratios

True Vac Bagging
Typically This involves the laminate being placed in the mould wet, either a pre-preg (pre-impregnated with Resin), using a wet out machine as the laminate is place, or just handlaying a wet laminate. numerous layers of special materials are then placed over the laminate;-
1 Peel ply - allows all the ensuing layers to peel off the final laminate
2 Bleeder film - allows the weep out of excess resin
3 Absorbtion mat - soaks up the excess resin
4 Vac bag
The entire pile is then placed under full vacuum while curing occurs. long Gel time materials are used so excess resin can be drawn off as the vacuum compresses the laminate and squeezes excess resin out. Usually the entire 4 extra layers above get binned.
Vacuum Infusion
The laminate is placed into the mould dry. A Peel ply, transfer medium and vac bag are placed over the top. this is all sealed down with the inclusion of Resin inlet lines and vacuum draw off lines. Max vac is then applied and testing done to ensure no leaks. any air leaking in at this time will defeat the purpose of infusion, to draw all the air out and have a void free laminate. Sometimes tracking down that leak can take considerable time. Once satisfied no leaks the resin be mixed up, fed into the lines and drawn in. A whole 30 ft boat can be infused in under an hour if set up right.
When cured, once again, all the extra layers as above are binned, as well as all the lines, which on a big boat, can be kilometers of Nylon tubing!
This process is often used on high performance parts and most aircraft parts we manufacture.
The Vacuum Bag process is used in production to increase product quality by reducing voids, decreasing weight, and obtaining a better fibre-to-resin ratio that will lead to stronger laminates. It is used for pressing cores into standard or high-tech laminates to ensure good adhesion (e.g. plyglass panels for truck and trailer manufacturers), or producing high-tech laminates giving extremely high strength to weight ratios. The vacuum ensures thorough wet-out of the fibre reinforcements, while excess resin is drawn off and absorbed into a 'bleeder' cloth. This type of laminate is usually for a specific task and is often comprised of expensive fibres such as Carbon and Kevlar. The vacuum bagging materials (peel ply, perforated film, bleeder cloth, and breather cloth) are all usually discarded after one article, adding to the expense.
Typically This involves the laminate being placed in the mould wet, either a pre-preg (pre-impregnated with Resin), using a wet out machine as the laminate is place, or just handlaying a wet laminate. numerous layers of special materials are then placed over the laminate;-
1 Peel ply - allows all the ensuing layers to peel off the final laminate
2 Bleeder film - allows the weep out of excess resin
3 Absorbtion mat - soaks up the excess resin
4 Vac bag
The entire pile is then placed under full vacuum while curing occurs. long Gel time materials are used so excess resin can be drawn off as the vacuum compresses the laminate and squeezes excess resin out. Usually the entire 4 extra layers above get binned.
Vacuum Infusion
The laminate is placed into the mould dry. A Peel ply, transfer medium and vac bag are placed over the top. this is all sealed down with the inclusion of Resin inlet lines and vacuum draw off lines. Max vac is then applied and testing done to ensure no leaks. any air leaking in at this time will defeat the purpose of infusion, to draw all the air out and have a void free laminate. Sometimes tracking down that leak can take considerable time. Once satisfied no leaks the resin be mixed up, fed into the lines and drawn in. A whole 30 ft boat can be infused in under an hour if set up right.
When cured, once again, all the extra layers as above are binned, as well as all the lines, which on a big boat, can be kilometers of Nylon tubing!
This process is often used on high performance parts and most aircraft parts we manufacture.
The Vacuum Bag process is used in production to increase product quality by reducing voids, decreasing weight, and obtaining a better fibre-to-resin ratio that will lead to stronger laminates. It is used for pressing cores into standard or high-tech laminates to ensure good adhesion (e.g. plyglass panels for truck and trailer manufacturers), or producing high-tech laminates giving extremely high strength to weight ratios. The vacuum ensures thorough wet-out of the fibre reinforcements, while excess resin is drawn off and absorbed into a 'bleeder' cloth. This type of laminate is usually for a specific task and is often comprised of expensive fibres such as Carbon and Kevlar. The vacuum bagging materials (peel ply, perforated film, bleeder cloth, and breather cloth) are all usually discarded after one article, adding to the expense.