|
2. Classification and
Code System
 |
Classification and code system of tin plate and black
plate are as follows.
|
Code System
|
Codes for tin plate and black plate are given in Table
1.
|
Classification
|
Code
|
| Black plate |
SPB
|
| Electro-tin plate |
ET
|
| Hot-dipped tin plate |
HT
|
<Table 1>Codes for black plate
and tin plate
|
Steel Type
|
Tin plate and black plate are classified
according to steel types as shown in Table 2.
|
Steel Type
|
Features
|
|
MR
|
Two methods of annealing, box annealing
and continuous annealing, are both adopted. Even
if the hardness value is same, other mechanical
properties may differ according to the annealing
method. Thus, purchaser may select the annealing
method after a close consultation with manufacturer.
|
|
L
|
This steel type rarely has any minor
constituents such as Cu, Ni, Cr or Mo. Thus it is
suitable for containers requiring enhanced corrosion
resistance. |
|
D
|
D steel is AI killed steel, which
is suitable for deep drawing purposes or for other
working applications, liable to create the Luder's
pattern. |
<Table2> Major steel types
of black plates
|
Temper Quality
|
Temper quality of tin plate
and black plate is classified as shown in Table 3.
|
Code
|
Target Rockwell Harness T
Scale, HR 30T
|
|
T-1
|
49±3
|
|
T-2
|
53±3
|
|
T-2.5
|
55±3
|
|
T-3
|
57±3
|
|
T-4
|
61±3
|
|
T-5
|
65±3
|
|
T-6
|
70±3
|
<Table 3 :Temper class of single
cold-rolled product >
|
Remarks:1. .
|
Temper quality of single cold-rolled
tin plate and black plate cannot be exactly defined
with one mechanical property. However, the Rockwell
harness number T-scale has been adopted as it is
a useful and reliable indicator of mechanical properties.
|
|
2..
|
It is possible to anneal either with
box annealing method or continuous annealing method.
Even if the hardness value is equal, other mechanical
properties may differ according to the applied annealing
method. Thus, purchaser may select the annealing
method after a close consultation with manufacturer.
If continuous annealing method is, the letters "CA"
should be added to the temper class code in Table
4 (e.g:T-4CA). |
|
3..
|
Unless otherwise specified by purchaser,
the hardness value of each temper class given in
Table 4 may be lowered, considering the age-hardening
caused by tin-coating and ensuing storage conditions.
|
Temper of double cold-rolled product
|
Code
|
Target Rockwell Hardness
T Scale HR 30T
|
Target Proof Stress (Reference)
Rolling Direction kgf/m² (N/m²)
|
|
DR-8
|
73
|
56(550)
|
|
DR-9
|
76
|
63(620)
|
|
DR-9M
|
77
|
67(660)
|
|
DR-10
|
80
|
70(690)
|
|
Remarks: 1.
|
All factors affecting the workability
of double cold-rolled tin plate and black plate
cannot be exactly enumerated. In this light, the
Rockwell harness number T-scale has been adopted
as a useful and reliable indicator of mechanical
properties. |
|
2.
|
Proof stress value can be converted
to be used as a reference when needed. The value
has been calculated from the spring back test result
in Appendix 2. |
|
3.
|
Two methods of annealing, box annealing
and continuous annealing, are both adopted. Even
if the hardness value is same, other mechanical
properties may differ according to the annealing
method. Thus, purchaser may select the annealing
method after a close consultation with manufacturer.
|
|
Surface Finish
|
Surface finish for tin plate
and black plate is classified as shown in Table 4.
|
Product
|
Symbol
|
Classification
|
Features
|
|
Single Cold-Rolled
|
B
|
Bright Finish
|
Smooth surface with
grindstone pattern finish |
|
R
|
Stone Finish
|
Surface
finish with directional grindstone pattern |
|
M
|
Matte Finish
|
Dull surface finish |
|
Double Cold-Rolled
|
R
|
Stone Finish
|
Surface finish
with directional grindstone pattern |
<Table 4: Classification of black
plate surface finish >
|
3. Temper Designation
|
Temper of single cold-rolled (reduced) tin
plate and black plate is expressed with the Rockwell hardness
number T-scale (HR30T). The hardness target is given in
Table 3. For manufacturing products not specified in Table
3, a consultation between buyer and seller is required.
|
4. Sizes and Shapes
Thickness and Thickness Tolerance
|
| Thickness : |
If the nominal thickness of black plate is under
0.50mm, it should be the multiple of 0.01mm. If
the nominal thickness is over 0.50mm, it should
be the multiples of 0.05mm. |
| Thickness Tolerance : |
Thickness tolerance of tin plate and black plate
is ±10% to the nominal thickness. Measurement area
is limited to any place within the 10mm range from
the edge. For double cold-rolled products, thickness
is measured within the 6mm range from the edge.
The disparity between this value and nominal thickness
is defined as the transverse thickness. The tolerance
is |
tn : Nominal thickness t6 : Thickness measured within
6mm from the side edge
|
Width Tolerance
Width tolerance must stay within mm of the
specified size. In case of mill edged black plate, the width
tolerance is in the range of mm.
Length Tolerance
Length Tolerance: Length tolerance should
fall within mm to the specified size. It is preferable to
stay within mm. Inner diameter of coil: The standard for nominal
inner diameter of coil and black plate coil should be 406mm,419mm
and 508mm.
Off-squaredness
|
|
Off-squaredness of a sheet is the ratio of A
to B as shown in the picture. A is the deviation
from the straight line drawn at a right angle
to the other side of the sheet. B is the length
of the perpendicular line. The ratio shall not
exceed 0.25%. Furthermore, it is preferable to
fall within 0 to 0.15%
|
|
Off-squaredness: A/B X100(%)
)
|
|
Camber
|
|
The camber of coil and black plate coil should
not exceed 1.5mm to any given 1000mm in length,
as shown in the picture
|
|
|
Flatness
Coil and black plate coil are placed on flat
sheet to measure the bow, center buckle, and edge wave. The
measurement shall not exceed 5mm.
5. Appearance
|
Tin plate and black plate must have consistent thickness.
The surface must be smooth and even, without any detrimental
flaws, dents, wrinkles, rust, etc. For coil and black
plate coil, welded parts and irregularity may exist since
there is no opportunity to remove such defects during
manufacturing. |
6. Packaging and Marking
|
Unit of packaging for coil and black plate coil that
passed the inspection shall be agreed upon by the buyer
and seller. Each bulk package shall be marked with the
following items. However, with an approval from the purchaser,
some items may be omitted. |
|
