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Quality Specifications

HOME > Corrugated Box Archive > Quality Specifications
Corrugated Fiberboard for Outer Packaging (KS A 1502)

01. Types

Types of boards are double faced corrugated board and double wall corrugated board.

[Table 1] Types of Corrugated Fiberboards

Type Symbol
Double Faced Corrugated Board Type 1 S-1
Type 2 S-2
Type 3 S-3
Type 4 S-4
Double Wall Corrugated Board Type 1 D-1
Type 2 D-2
Type 3 D-3
Type 4 D-4
Type 5 D-5

02. Quality and Materials

Quality

Boards must be uniform and with no adhesive defect, flute defect, contamination or physical damages that may
impair its use and pass burst strength, flat crust and moisture tests when tested according to [Table 2].

[Table 2] Quality Standard of Corrugated Fiberboard

Type Symbol Burst Strength
(kgf/㎠ )(kPa)
Flat Crush kgf/50mm(KN/m) Moisture (%)
A Flute B Flute C Flute
Double Faced
Corrugated
Board
Type 1 S-1 6.5 (638)
Greater than
17.4 (3.41)
Greater than
16.8 (3.30)
Greater than
17.1 (3.35)
Greater than
10.0 ± 2.0
Type 2 S-2 8.0 (785)
Greater than
18.0 (5.53)
Greater than
17.5 (3.43)
Greater than
17.7 (3.47)
Greater than
Type 3 S-3 12.0 (1177)
Greater than
26.1 (5.12)
Greater than
25.4 (4.98)
Greater than
25.7 (5.04)
Greater than
Type 4 S-4 16.0 (1570)
Greater than
36.4 (7.14)
Greater than
35.6 (6.98)
Greater than
36.0 (7.06)
Greater than
Type Symbol Burst Strength
(kgf/㎠ )(kPa)
Flat Crush kgf/50mm(KN/m) Flat Crush (%)
AB Flute BC Flute
Double Wall
Corrugated
Board
Type 1 D-1 8.0 (785)
Greater than
25.3 (4.46)
Greater than
25.0 (4.90)
Greater than
10.0 ± 2.0
Type 2 D-2 10.0 (981)
Greater than
27.0 (5.29)
Greater than
26.5 (5.20)
Greater than
Type 3 D-3 14.0 (1373)
Greater than
32.6 (6.39)
Greater than
32.4 (6.35)
Greater than
Type 4 D-4 18.0 (1766)
Greater than
43.5 (8.53)
Greater than
43.2 (8.47)
Greater than
Type 5 D-5 22.0 (2159)
Greater than
51.1 (10.02)
Greater than
50.7 (9.94)
Greater than

* Burst Strength (kgf/㎠)(kPa) : Burst strength of board when dry.
* Moisture (%) : Moisture level shall be measured after 30 to 60 minutes of cutting the board.

Notes
- Burst and flat crush strengths for boxes that will be shipped in export containers shall match the specification
   in [Table 2]. Burst and flat crush strengths for boxes for regular exportation shall be one level higher than the
   specification in KS A 1531 [Table 1].
- Flat crust strength for triple boards for export shall exceed 95 kgf/50mm.
- Burst strength of board shall be determined by the following equation.
Burst strength of double face corrugated board = [Burst strengths of front liner + back liner] * 0.95
Burst strength of double wall corrugated board = (Burst strengths of front liner + middle liner + back liner)
* 0.95

If a medium paper is used as the middle liner, base weight of the paper shall be 120g/㎡, with burst strength of 1.0.

- Flat crust strength shall be determined by the following equation.

P1 : Flat crust strength of double faced corrugated board, kgf/50mm
P1 : Double wall strength of double faced corrugated board, kgf/50mm
Ro : Burst strength of front liner, kgf
Rm : Burst strength of medium paper, kgf
Ri : Burst strength of back liner, kgf
Rc : Burst strength of middle liner, kgf
Tx : If A flute, TA=1.6 / if B flute, TB=1.4 / if C flute, TC=1.5

- Determine flat crust strength by assuming medium paper = 120kg/㎡, grade C for Types 1 and 2 and grade A
   for Type 3.
- For converting from kgf/50mm to KN/m, multiply 0.1962.
Materials

- Use liners specified in KS M 7502 (Liners for Corrugated Fiberboards) or of higher grade.
- Use medium papers specified in KS M 7576 (Medium Papers for Corrugated Fiberboards) or of higher grade.
- Use adhesives with adhesive strength of starch glue or higher.

03. Shape and Size

There shall be 3 flute types and number of flutes, as shown in [Table 3].

[Table 3] Flute Type and Number of Flutes

Flute Type Symbol No. of Flutes / 30cm
A Flute A F 34 ± 2
B Flute B F 50 ± 2
C Flute C F 40 ± 2
Corrugted Fiberboards for Shipping Containers (KS A 1531)

01. Type

There are 5 types of corrugated boxes - 4 types of double faced corrugated boxes and 1 type of double wall
corrugated box - and comply with [Table 4].

[Table 4] Types of Corrugated Boxes

Symbol Type of Corrugated
Fiberboard Used
Packing Restriction
Max Weight, kg Max Inner
Dimension, cm
Double Faced
Corrugated Box
Type 1 CS-1 Type 1 Double Faced
Corrugated Fiberboard
10 120
Type 2 CS-2 Type 2 Double Faced
Corrugated Fiberboard
20 150
Type 3 CS-3 Type 3 Double Faced
Corrugated Fiberboard
30 175
Type 4 CS-4 Type 4 Double Faced
Corrugated Fiberboard
40 200
Double Wall
Corrugated Box
Type 1 CD-1 Type 1 Double Faced
Corrugated Fiberboard
20 150
Type 2 CD-2 Type 2 Double Faced
Corrugated Fiberboard
30 175
Type 3 CD-3 Type 3 Double Faced
Corrugated Fiberboard
40 200
Type 4 CD-4 Type 4 Double Faced
Corrugated Fiberboard
50 250
Type 5 CD-5 Type 5 Double Faced
Corrugated Fiberboard
60 275

* Packing restrictions are based on 0201 type boxes specified in KS A 1003.
* Max inner dimension is the sum of inner width, depth and height.
* Packing restrictions for boxes for shipping containers and for regular exportation shall be as same as indicated in [Table 4]
   and one level higher than indicated in [Table 4], respectively.

02. Form

Base form of corrugated boxes shall be 0201 types specified in KS A 1003. However, it may vary depending
on the contents to be packed.

03. Quality

Boxes must be uniform and with no adhesive defect, flute defect, contamination or physical damages that may
impair its use.
Burst strength of boxes shall be tested according to 07. Required strength shall be determined by the concerned
parties.

04. Materials

Corrugated fiberboard

Corrugated fiberboard here refers to the Corrugated Fiberboard for Shipping Containers specified in KS A 1502.

Box Sealing

For sealing boxes, use metal wire, packing tape or adhesive.

Metal Wire : Rust-proofed and uniform steel wire with breadth of 1.5mm or higher
Packing Tape : Tape specified in KS A 1522 or of higher grade, with breadth of 50mm or higher.
Adhesive : Adhesive shall have bonding strength equal to or higher than metal wire or tape.

05. Structure

- Each side of box shall be perpendicular to another - this rule shall not apply to modified boxes. Boxes shall be free
  of folding marks and serious defects and damages on the board surface.
- Boxes shall be sealed using an adhesive, metal wire or packing tape with sufficient binding strenfth.
- Allowance shall be 30mm for double faced corrugated boxes and 35mm for double wall corrugated boxes.
  The distance between wires shall be within 65mm. The wire shall be no further than 25mm from either top or
  bottom of the box.

06. Dimensions

Box dimensions shall be of inner measurements expressed in width x depth x height format. Allowance for
error for each shall be ±1%. Max allowances is ±3mm for double faced corrugated boxes and ±5mm for double
wall corrugated boxes. However, allowances for dimensions can be changed by the concerned parties.

07. Flat Crust Strength Test

The samples shall be pre-processed according to KS M 7012 and tested according to KS A 1012.
Direction of force shall be vertical with max force expressed in N{kgf}.

08. Inspection

Inspection shall be conducted on form, quality, material, structure and dimensions in accordance with
items 02 through 06.

09. Labeling

The following shall be labelled on the box.

Type of corrugated box or its symbol
Date and year of manufacture or its code
Name or abbreviation of manufacturer