05/03/2024 11:48

What is sliced veneer? Technical requirements for sliced veneer in Vietnam under TCVN 4358:2021

What is sliced veneer? Technical requirements for sliced veneer in Vietnam under TCVN 4358:2021

What is sliced veneer? What are the technical requirements for sliced veneer in Vietnam under TCVN 4358:2021? _Nguyen Binh (Ca Mau)

Hello, Lawnet would like to answer as follows:

1. What is sliced veneer?

According to the regulations in TCVN 4358:2021, sliced veneer is defined as follows:

Sliced veneer: It is a thin sheet of wood created by the slicing method.

In addition, sliced veneer produced by different methods will have specific names:

Radial sliced veneer:

- Radial sliced veneer is created by slicing parallel to the longitudinal axis of the tree and perpendicular to the growth rings.

- In terms of the growth rings, the lines on the longitudinal cut of the wood grain are in the form of parallel straight lines.

- In terms of the wood rays, on at least 3/4 of the surface area of the sliced veneer, the wood rays are in the form of darker or lighter streaks compared to the surrounding wood and perpendicular to the longitudinal axis of the wood grain.

Tangential sliced veneer:

- Tangential sliced veneer is created by slicing parallel to the longitudinal axis of the tree and tangential to the growth rings.

- In terms of the growth rings, the lines on the surface of the sliced veneer are in the form of V-shapes or curves.

- In terms of the wood rays, on the surface of the sliced veneer, the wood rays are in the form of darker or lighter streaks compared to the surrounding wood and aligned along the longitudinal axis of the wood grain.

Semi-radial sliced veneer:

- In terms of the growth rings, on the surface of the sliced veneer, at least 3/4 of the surface area consists of parallel straight lines.

- In terms of the wood rays, on the surface of the sliced veneer, at least 1/2 of the surface area consists of wood rays in the form of darker or lighter streaks compared to the surrounding wood, inclined or aligned with the longitudinal axis of the wood grain.

2. What are the technical requirements for sliced veneer in Vietnam under TCVN 4358:2021?

According to the regulations in TCVN 4358:2021, the technical requirements for sliced veneer are as follows:

Technical requirements for dimensions and dimensional tolerances:

The dimensions and dimensional tolerances of sliced veneer must comply with the following regulations:

Veneer size

Size

Tolerances

 

< 0.20

± 0.02

 

0.20 ÷ 0.50

± 0.03

1. Thickness, mm

0.51 ÷ 1.00

± 0.04

 

1.01 ÷ 2.00

± 0.06

 

> 2

± 0.08

2. Width, mm

≥ 60

+5

0

3. Length, mm

≥ 500

+ 10

(Advanced rate (+50) mm)

0

Note: The sizes listed are commonly used sizes. Depending on the agreement between the two parties and usage requirements, many different sizes can be offered

Technical requirements for appearance quality in Vietnam

The external quality of sliced veneer is divided into 3 categories: standard grade, grade 1, and special grade. The external quality is defined as follows:

Criteria

Quality level

Special

Type 1

Standards

1. Living eyes

Broadleaf wood

Largest eye diameter, mm

ten

20

Unlimited

Coniferous wood

5

ten

20

2. Dead eyes, holes, sticky shells, plastic bags

Dead eyes, holes, shells, plastic bags

Total quantity per 1 meter length

Width ≤ 120 mm

0

first

2

Width > 120 mm

0

2

3

Half-living eyes

Largest eye diameter, mm

Not allowed

10 (less than 5 does not count)

20 (less than 5 does not count)

Dead eyes, moth holes, holes

Largest eye diameter, mm

Not allowed

Not allowed

4 (less than 2 does not count)

Stick to the shell

Maximum length, mm

Not allowed

Not allowed

20 (less than 10 does not count)

Plastic bag

15 (less than 5 does not count)

30 (less than 10 does not count)

3. Uneven color, discoloration, discoloration

Color deviation

Very unclear

Unclear

Clear

4. Section

Observation, level

Not allowed

Not allowed

Not allowed

5. Cracks

Maximum crack width, mm

Private

Open

Private

< 0.2

Private

< 0.5

Percentage of crack length compared to veneer length (%)

5

Not allowed

ten

5

15

ten

6. Knife marks, cuts, scratches

Feel with eyes and hands, level

Not allowed

Unclear

Small

7. Defects, damage to edges and corners

Not allowed within the tolerance size of the veneer

Note:

1. The color deviation of decorative veneer is determined through discussion between the two buyers and sellers. If it is necessary to determine, a colorimeter is used. Distinguish levels of color deviation as follows: Total color deviation <1.5: Very unclear; Total color deviation 1.5~3: Unclear; Total color deviation 3~6: Clear.

2. Depending on the agreement between the two buyers and sellers and usage requirements, defects other than those falling under the technical requirements on appearance quality may be allowed.

Technical requirements for the moisture content of sliced veneer:

Before being put into use, sliced veneer must have a moisture content of 8% - 16%.

Technical requirements for the surface roughness of sliced veneer:

Standard TCVN 4358:2021 uses parameters Ra and Rz to evaluate the surface roughness of sliced veneer. The requirements for surface roughness of sliced veneer are as follows:

Type of wood

Parameter value, µm

Average error R a

Undulating height R z

1. Circular broadleaf wood

≤ 30

≤ 250

2. Broadleaf and coniferous wood

≤ 20

≤ 150

More details can be found in TCVN 4358:2021.

Hua Le Huy
77


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