ДОМОЙ
НАШИ ПАРТНЕРЫ
НОВОСТИ
КОНТАКТЫ
Участники рынка
COMPOSITES MARKET
World's best independent web-portal
about advanced composites
Market participants
B-Composites
recommends
Professional translation
English-Russian
Affordable prices
Articles
Websites
Instructions
Advertizing materials
Correspondence
All translators are native Russians and have:
- Engineering education
- Additional education in marketing
- Perfect Russian literary language
Basalt fiber: Hand lay up
The largest number of reinforced plastics composite products are produced by the hand lay-up process. A few examples of this processes uses are: boats, portable toilets, picnic tables, car bodies, diesel truck cabs, hard shell truck bed covers and air craft skins and interiors. The hand lay-up process is labor intensive plus the plastic resins produce toxic fumes requiring well ventilated facilities and protective equipment for workers. And, since the workers seem to want to be paid more when around toxic things, they may want more pay.
The hand lay-up process produces parts from an open, glass reinforced, mold. The mold surface is treated with several layers of release wax and then spray coated with a pigmented polyester resin called a gel coat. The surface of the mold will be duplicated by the gel coat. Over the gel coat, glass fiber is layered. Each layer is saturated with polyester resin that is specifically formulated to cure at room temperature. The polyester resin must be catalyzed 2% by weight. The catalyst is a toxic and corrosive peroxide. Each glass layer is pressed by hand with rollers to work the polyester resin into the glass fiber. Three to nine layers are added and allowed to cure depending on the desire strength of the part. Once the polyester is cured, the part is removed from the mold. The part requires trimming and post mold surface preparation. In the production of the high performance airplane, both carbon fiber and epoxy plastic are used.
Hand lay-up parts can consist of any size or configuration. Moreover, the process does not require any special tools. Parts can be easily fabricated as a weekend backyard project. Molds can be easily modified, cut into part for prefabrication and applied to create various surface textures. The rigid properties of the final product require that under cuts and straight wall be eliminated. Any openings must be machined in post molding operations. All corners must have somewhat large radius. The structure is often stiffened with the additions of honeycomb, balsa or rigid foam blocks.
Below you can find an instruction of production of boats using hand lay up process:
1. PREPARING THE MOLD
Remove any dust and dirt from mold. If mold is of plaster, wood, or new fiberglass, apply soft wax and
buff with soft towel. Spray or brush with PVA, parting compound and allow to dry. If mold material is
glass, metal, ceramic, or well-cured fiberglass, apply three coats of hard wax, carnauba type, buffing
between each coat.
2. APPLYING THE GEL-COAT
1. If gel-coat is to be brushed on, allow first coat to cure and then apply the second coat to make
sure there are no light spots.
2. If gel-coat is to be sprayed on with a gel-coat gun, spray up to a thickness of .015” to 020”.
When gel-coat has cured long enough that your fingernail cannot easily scrape it free (test at edge
of mold where damage will not show on part) then proceed with next step.
3. LAY-UP SKIN COAT
Cut ? or 1 oz. mat to cover part. Brush catalyzed resin over gel-coat, then apply the mat. Work with roller
adding more resin where necessary until all white areas in mat fibers have disappeared and all air bubbles
have escaped. Resin-rich areas weaken the part. Where rollers will not reach, brushes must be used.
When this step is complete, clean all tools in acetone. Allow skin coat to cure before next step.
4. LAYING FIBERGLASS REINFORCEMENT
For a 12 ft. boat, two layers of 1? oz. or 2 oz. mat may be adequate, depending upon design. For a 14 ft.
boat, an additional layer of woven roving will add considerable strength. Apply each layer as in step 3, but
it will not be necessary to wait for curing between these layers. Be sure to shake all acetone out of brushes
and rollers before applying resin. Acetone drips can result in uncured spots in the lay-up.
5. TRIM
On a small lay-up, the fiberglass laminate which hangs over the edge of the mold can be trimmed off easily
with a razor knife if you catch the “trim stage,” of the period after the lay-up has gelled but before it has
hardened. On a larger lay-up, it can be trimmed with a saber saw and coarse sand paper.
6. CURE
May take from two hours to overnight, depending upon turnover desired, temperature, canalization, and
nature of the part. If laid up in a female mold, longer cure will affect shrinkage and easier parting. In the
case of the male mold, the part comes off more easily before it shrinks appreciably. If the part is subject to
warping, a longer cure may be necessary. In any case, when the part is removed it should be supported in
its desired shape until fully cured.
7. REMOVE PART FROM MOLD
First, examine the trim edge all the way around the mold and make sure there is no resin bridging the line
between the mold and the part. Sand this edge where necessary. Then wooden wedges, such as “tongue
sticks,” can be pushed into the edges to start the separation. Continue separation by pulling and flexing. In
some cases it is necessary to drill a small hole in the mold and apply air or water pressure.
8. FINISH
Trim edges and back of part may need to be fine-sanded and coated with surfacing resin or gel coat.
9. GEL-COAT PROBLEMS
Wrinkling of the gel-coat may be due to the following reasons:
1. Gel-coat is too thin in spots so it does not completely cure.
2. Insufficient hardener added, or hardener not mixed well enough. It is best to use twice as much
hardener in gel-coat as in lay-up resin at the same room temperature since the gel-coat goes on
thinner than a mat lay-up.
3. Gel-coat has not cured long enough before mat lay-up.
4. Acetone from tools drips onto gel-coat or into skin lay-up.
Source: http://www.clubkitclearcote.com/instructions/Hand%20Layup.pdf; http://www.pslc.ws/macrog/mpm/composit/fiber/process/handlay.htm
Composites market
|
Terminology
|
Matrices
|
Technologies and products of further processing
|
Basalt fiber
|
The main basalt products
|
Continuous basalt fiber
|
Production technologies
|
Manufactures
|
Products
|
Sizing
|
Advantages
|
Applications
|