Welde Bulgaria - Raw plywood

plywood, raw plywood, film-faced, film-faced plywood, wire-mesh, wire-mesh plywood, pp-faced plywood, hardboard, natural fibreboard, embossed hardboard, .

Production of construction plywood, furniture plywood, packaging plywood and hardboard (Natural fibreboard)

Plywood

Raw plywood Film-faced plywood PP-faced plywood Sound-isolating plywood

Hardboard

Natural fibreboard Embossed hardboard

Other products

Raw plywood

The plywood panels are made by gluing together of 3 or more veneer sheets (plies). The grain of each ply is perpendicular to the plies above and below it. The phenol formaldehyde resin used as a gluing agent gives to the bonding a high resistance of weather conditions, microorganisms, cold and hot water. The cross-bounded construction of veneers guarantees exceptionally good mechanical qualities of the plywood panel such as: strength, stability, high resistance of strokes, vibrations and tension.
The plywood panels react far better to temperature influence than the metal and plastic materials. They are more stable under cold than under heat. The temperature range that can be used with no change in the appearance and mechanical characteristics is wider than 100°С.

The plywood panels are suitable for noise insulations. As the effectiveness of the insulation depends on the density of the insulation material, the plywood panels have a better ratio of density-noise insulation, compared to other materials (EN 13986).

For plywood production in Welde Bulgaria the most used species is Robusta poplar. But species like beech, birch and soft wood are also possible to be used. Various wood species can be combined in composing the plywood panels.
The formaldehyde emissions are low and correspond to the prescriptions of EN 717-2., i.e. the regulations of E1 class (the most safety one).

Sizes

The length is normally twice the width of a panel.
The standard sizes are:

Length, mm: 2500 ± 2.0;
Width, mm: 1250 ± 2.0;
Thickness, mm: 4; 6; 8; 10; 12; 14; 15; 16; 18; 21; 24; 25; 27; 28; 30.

The production equipment of Welde Bulgaria as per customer’s request enables additional treatment of the panels to be done: sanding, calibration, or cutting to size. The density of the poplar plywood is 450-500 кг/м3.

Thickness, mm	Weight, kg		Number of sheets in a package
Thickness, mm	per sheet	per package	Number of sheets in a package
4	6	1320	220
6	9	1480	168
8	12	1480	126
10	15	1480	101
12	18	1500	84
14	20	1480	72
16	23	1480	64
18	26	1450-1500	56
21	30	1450-1500	48
24	35	1480	42
28	41	1480	36
30	43	1480	34

Note: The values refer to plywood panels of 1250 х 2500 mm sizes.

Quality according to the appearance of the surface (acc. to the EN 635).

Grading of the plywood panels according to the surface appearance is performed based on two criteria – number of the defects as natural characteristics of wood, and defects caused over the production process.
The qualities acc. to the EN 635-3, in force since 2004, are as follows: E, I, II, III, IV. They correspond to the A, AB, B, BB, C qualities of the former standard BDS 384-76.

Categories of characteristics		Appearance class
		E	I	II	III	IV
Pin knots )*		Practically absent	3/m2 permitted	Permitted
Sound intergrown knots			Permitted up to an individual diameter of:
			15 mm provided their cumulative diameter does not exceed 30 mm/m2	50 mm	60 mm	Permitted but see Note.
			Such knots may have splits provided they are:
			very slight	slight
Unsound or non-adhering knots and knots holes			Permitted up to an individual diameter of:
			6 mm if filled and up to a number of 2/m2	5 mm if unrepaired 25 mm if filled and up to a number of 6/m2	40 mm	Permitted but see Note.
Splits	open		Permitted if less than:
			1/16	1/3	½	Length unlimited
			of panel length up to an individual width of:
			3 mm	10 mm	15 mm	25 mm
			and up to a number of:
			3/m	3/m	3/m	unlimited
			of panel width
			if properly filled	All splits greater than 2 mm in width to be filled
	closed		Permitted
Anomalies due to insects, marine borers, and parasite plants		Not permitted	Not permitted	Marks of parasitic plants not permitted. Insects and marine borer holes permitted up to a:		Permitted but see Note.
				diameter of 3 mm vertically to the plane of the panel up to a number of 10/m2	width up to 15 mm and a length of 60 mm up to a number of 3/m2
Resin pockets and inbark			Not permitted	Permitted up to a width of		Permitted but see Note.
				6 mm if properly filled	40 mm
Resin streaks			Not permitted	Permitted if slight	Permitted
Irregularities in the structure of the wood		Practically absent	Permitted		Permitted
			if very slight	if slight
Discoloration which is not wood destroying			Permitted if low contrast		Permitted
Fungal decay, wood destroying		Not permitted	Not permitted
Other characteristics		Practically absent	To be considered under the category which they most closely resemble
) Pin knots: sound intergrown knots of no more than 3 mm diameter NOTE:* Characteristics inherent to wood ate permitted provided that they do not impair the serviceability of the panel.

Classification according to characteristics inherent in wood.

E Quality	I Quality	II Quality
III Quality	IV Quality

Categories of defects	Appearance class
	E	I	II	III	IV
Open joints	Not permitted	Not permitted	Permitted up to a width of:
			3 mm	10 mm	25 mm
			and up to a number of:
			1/m	2/m	unlimited
		of panel width with joints
			filled if more than 1 mm in width	unfilled	unfilled
Overlaps		Not permitted	Permitted up to a number of 1/m2 and up to 100 mm length	Permitted up to a number of 2/m2	Permitted but see Note
Blisters		Not permitted
Hollows, imprints and bumps		Not permitted	Permitted if slight	Permitted
Roughness		Not permitted	Permitted if slight	Permitted
Sanding through		Not permitted		Permitted up to an extend of:
				1 %	5 %
				of panel surface
					but see Note
Glue penetration		Not permitted	Permitted		Permitted but see Note
			if slight and occasional	up to an extent of 5 % of the panel surface
Foreign particles		Not permitted	Ferrous particles not permitted
Repairs a) Patches b) Shims c) Synthetic fillers	Practically without defects	Permitted if properly made and tightly filled up to a number of:
		5/m2	unlimited
	Not permitted	Not permitted	is permitted with limits of the category which it most closely resembles		unlimited
Defects at the edges of the panel due to sanding or sawing	Practically without defects	Permitted up to			Permitted but see Note
		2 mm	5 mm	5 mm
		from the edge
Other defects		To be considered under the category which they most closely resemble
NOTE: Manufacturing defects are permitted provided that they do not impair the serviceability of the panel.

Classification according to manufacturing defects.

Physical and mechanical characteristics

Moisture of the plywood (acc. to the EN 322): 10 ± 2 %.
Squaredness variation after trimming: up to 1 mm/m.
Variation out of the rated length and width (acc. to the EN 315): ± 3.5 mm.

Variation out of the rated thickness (acc. to the EN 315):

Rated thickness(t), mm	Non-sanded panels				SANDED PANELS
	Variation out of the thickness in a panel, mm		Variation out of the rated thickness, Mm		Variation out of the thickness in a panel, mm		Variation out of the rated thickness, mm
	EN 315	Welde Bulgaria	EN 315	Welde Bulgaria	EN 315	Welde Bulgaria	EN 315	Welde Bulgaria
≥ 3 ≤ 12	1.0	0.8	+ (0.8 + 0.03 t) - (0.4 + 0.03 t)	+ 0.5 -0.4	0.6	0.3	+ (0.2 + 0.03 t) - (0.4 + 0.03 t)	+ 0.2 - 0.4
> 12 ≤ 25	1.5	1.0	+ (0.8 + 0.03 t) - (0.4 + 0.03 t)	+ 0.8 - 0.5	0.6	0.3	+ (0.2 + 0.03 t) - (0.4 + 0.03 t)	+ 0.4 - 0.6
> 25 ≤ 30	1.5	1.0	+ (0.8 + 0.03 t) - (0.4 + 0.03 t)	+ 1.0 - 0.8	0.8	0.3	+ (0.2 + 0.03 t) - (0.4 + 0.03 t)	+ 0.5 - 0.8
> 30	1.5	1.2	+ (0.8 + 0.03 t) - (0.4 + 0.03 t)	+ 1.3 -1.0	0.8	0.3	+ (0.2 + 0.03 t) - (0.4 + 0.03 t)	+ 0.5 - 1.0

Bonding strength:
- Dry plywood: over 2.0 MN/m2;
- After one hour stay in hot water: over 1.0 MN/m2.
Formaldehyde emission class: Е1.
Water resistance of the used resin: WBP mark

Application

In the building industry.
In the furniture industry.
Vessel production.
Wagon production.
Automobile production.
Packaging.
Sports equipment (ski, snowboards, etc.).