Plywood for the building industry "Welde Film Robusta"
The plywood for the building industry "Welde Film Robusta" is produced according to the European Standards (EN).
The plywood faces are covered with special water-repelling resin paper under the influence of high temperature and pressure. This procedure of paper application protects the plywood panels against moisture. The edges of the plywood panels are also protected against moisture with suitable paint.
Plywood panels covered with smooth water-repelling resin paper are especially suitable for outdoor applications – mostly for building reinforced concrete forms.
Sizes
- Length, mm: 2500; 2440 ± 2.0;
- Width, mm: 1250; 1220 ± 2.0;
- Thickness, mm: 12; 15; 18 and 21 rated thickness.
Other thickness values are also possible, as per customer’s request. Start-up of the over-laying line of the German company Bürkle will enhance the production of sizes up to 3000 x 1500 mm, as well. The permitted variation in the nominal thickness is the same as for the raw plywood.
Grading according to the appearance of the surface
The qualities according to the appearance of the surface are defined as per the Technical Specifications of the mill. According to the defects on the surface the plywood is separated in Extra, Standard, or Economy qualities.
| Name of defects |
Norms of permittance |
| Extra quality |
Standard |
Economy |
Panel squaredness
Variation |
Permitted up to 1 mm for each linear meter of panel edge |
| Colour variation |
Permitted |
Permitted |
Permitted |
| Lower paper bond strength and markings of face/core defects on the paper |
Permitted for up to 15 mm for knots and 5 mm for splits for total of 2 per sqm. |
Permitted for up to 25 mm for knots and 10 mm for splits for total of 5 per sqm |
Permitted |
| Missing paper |
Not permitted |
Up to 1% of total surface |
Up to 2% of total surface |
| Surface swelling |
Not permitted |
Not permitted |
Permitted up to 1 per sqm with diameter up to 50 mm |
Characteristics
- Physical and mechanical durability
- Resistance to moisture and friction
- Sizes remain stable over time
- Low level of swelling
- Multiple panel use when properly used and stored
- Minimal material loss over time of use
- Labour cost saving
- Assures high quality of concrete surface
- Easy to clean after use
Physical and mechanical specification
| ¹ |
Criteria |
Veneer combination value |
Poplar/poplar
or beech/poplar |
beech/poplar/ beech |
| 1. |
Density, kg/m3 |
450-500 |
550-670 |
| 2. |
Bending module of elasticity, N/mm2:
- Along the wood grain Å║
|
4900 |
8000 |
- Perpendicular to the grain Å ┴
|
4000 |
4000 |
| 3. |
Resistance to bending in N/mm2:
- Along the wood grain Ω ║ |
40 |
65 |
- - Perpendicular to the grain Ω ┴
|
30 |
48 |
| 4. |
Resistance to friction
/Taber – number of rotations/ |
350-400 |
350-400 |
User’s instructions
- The faces of the panels should be protected until their usage.
- Panels should be stored in a dry place over leveled crossbars.
- Panels should be carefully handled so that the faces and edges are not damaged.
- Cutting and drilling of the panels to be done with appropriate tools to avoid damaging of the panel surfaces.
- After cutting and/or drilling, the fresh surfaces should be sealed with water-resistant paint.
- Prior to using the panels, shuttering oil should be used for easier panel removal.
- It is recommended upon building the shuttering structure, only specially designed mounting elements to be used.
Important!
Film-faced plywood is designed to be used 30-50 times.
The effective multiple and cost-saving use is utterly dependent on the proper panel handling and care!
Based on the experience, Welde Bulgaria specifies the following recommendations for plywood application which is a guarantee for reliable use under conditions of maximal loading in the building industry.
| No |
Support distance,
m |
Thickness of film-faced plywood,
mm |
Max. recommended thickness of the reinforced concrete slab,cm |
| 1 |
0.50 |
21 |
16 – 18 |
| 2 |
0.50 |
18 |
14 – 16 |
| 3 |
0.625 |
21 |
12 – 14 |
| 4 |
0.625 |
18 |
< 12 |
Note: Data refers to poplar plywood.
Application
- In the building industry - for shuttering.
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