Technical Field
[0001] The present invention relates to an iron-based mixed powder suitable for use in powder
metallurgy. In particular, the present invention is intended to increase green density
and is also intended to advantageously reduce the ejection force necessary to withdraw
a green compact from a die after compaction.
Background Art
[0002] In a powder metallurgy process, source powders are mixed together; the mixture is
transferred, is filled into a die, and is then pressed into a formed body (hereinafter
referred to as a green compact); and the green compact is withdrawn from the die and
is then subjected to a posttreatment such as sintering as required.
In the powder metallurgy process, in order to achieve an increase in product quality
and a reduction in production cost, it is necessary to ensure all of high powder flowability
in a transferring step, high compressibility in a pressing step, and low ejection
force in a step of withdrawing the green compact from the die.
[0003] As for techniques for improving the flowability of iron-based mixed powders, Patent
Literature 1 discloses that the flowability of an iron-based mixed powder can be improved
by adding a fullerene, which serves as a carbon supply component, thereto.
Furthermore, Patent Literature 2 discloses a technique for improving the flowability
of a powder composition for metallurgy by adding a particulate inorganic oxide with
an average particle size of less than 500 nm thereto.
However, the use of these techniques is insufficient to achieve high compressibility
and low ejection force while flowability is maintained.
[0004] In order to increase the density of a green compact or in order to reduce the ejection
force thereof, it is effective to use a lubricant that has ductility and that is soft
at a temperature at which an iron-based mixed powder is pressed. This is because the
lubricant seeps out of the iron-based mixed powder during pressing to adhere to a
surface of a die and therefore reduces the friction between the die and the green
compact.
However, the lubricant has ductility and therefore is likely to adhere to particles
of an iron powder and powder for an alloy. Hence, there is a problem in that the flowability
and filling ability of an iron-based mixed powder are impaired.
[0005] The blending of the above carbon material, fine particles, and lubricant reduces
the theoretical density (the density determined assuming that the voidage is zero)
of the iron-based mixed powder to cause a reduction in green density; hence, it is
not preferable to blend large amounts of these materials.
It has been extremely difficult to balance the flowability of a conventional iron-based
mixed powder, high green density, and low ejection force.
[0006] As for techniques relating to additives for iron-based mixed powders, Patent Literature
3 discloses a technique in which a powder of iron oxide (such as mill scale) is added
to a powder of finish-reduced iron to control a dimensional change of a sintered body.
As for techniques relating to iron oxide powders, Patent Literature 4 discloses a
method for synthesizing micaceous iron oxide (MIO) known as a pigment for rust-proof
paints for steel materials. According to the method disclosed in Patent Literature
4, primary particles of α-iron oxide that have a size of 1 µm to 100 µm and an aspect
ratio of 5 to 30 are obtained.
Related Art Document
Patent Literature
[0007]
PTL 1: Japanese Unexamined Patent Application Publication No. 2007-31744
PTL 2: PCT Japanese Translation Patent Publication No. 2002-515542
PTL 3: Japanese Unexamined Patent Application Publication No. 8-325667
PTL 4: Japanese Unexamined Patent Application Publication No. 3-131526
Summary of Invention
Problems to be Solved by the Invention
[0008] The present invention has been developed in view of the aforementioned circumstances
and has an object to suggest an iron-based mixed powder for powder metallurgy. The
iron-based mixed powder can accomplish both an increase in product quality and a reduction
in production cost in such a way that the density of a green compact is increased
by increasing the flowability of the iron-based mixed powder and ejection force is
greatly reduced after compaction.
Solution to Problem
[0009] The inventors have investigated various additives for use in iron-based powders for
the purpose of achieving the above object.
As a result, the inventors have found that the addition of an appropriate amount of
oxide particles with an average size of 0.5 µm or more to an iron-based powder provides
significantly improved flowability and also provides improved green density and ejection
force.
The present invention is based on the above finding.
[0010] The present invention is as summarized below.
- 1. An iron-based mixed powder for powder metallurgy contains an iron-based powder
and 0.01% to 5.0% by mass of particles of an oxide that have an average size of 0.5
µm or more.
[0011] 2. In the iron-based mixed powder for powder metallurgy specified in Item 1, the
oxide contains at least one selected from the group consisting of iron, aluminum,
and silicon.
Needless to say, the oxide refers to an oxide forming the oxide particles.
[0012] 3. The iron-based mixed powder for powder metallurgy specified in Item 1 or 2 further
contains powder for an alloy.
[0013] 4. The iron-based mixed powder for powder metallurgy specified in any one of Items
1 to 3 further contains an organic binder.
[0014] 5. The iron-based mixed powder for powder metallurgy specified in any one of Items
1 to 4 further contains a free lubricant.
Advantageous Effects of Invention
[0015] According to the present invention, not only increased flowability but also high
green density and low ejection force can be achieved by adding an appropriate amount
of oxide particles having an average size of 0.5 µm or more to an iron-based powder.
This results in an increase in production efficiency and a reduction in production
cost.
Brief Description of Drawing
[0016] [Fig. 1] Fig. 1 is a schematic view illustrating the aspect ratio of powder.
Description of Embodiments
[0017] The present invention will now be described in detail.
In the present invention, oxide particles are used as a component for improving the
flowability of an iron-based powder. The reason is as described below.
Common iron-based mixed powders contain about 1% by mass of organic lubricants for
the purpose of increasing the flowability of powder or decreasing the ejection force
of green compacts. The organic lubricants have a specific gravity of about 1.0 and
are significantly lower in specific gravity than iron powders, which have a specific
gravity of 7.8. In general, in the case of mixing powders that are significantly different
in specific gravity from each other, segregation occurs during mixing to cause a reduction
in flowability or differences in properties between lots.
Thus, in the case of mixing different types of powders, it is important that the difference
in specific gravity therebetween is as small as possible.
[0018] When the oxide particles used herein are made of, for example, iron oxide (hematite),
the oxide particles have a specific gravity of 5.3 and are higher in specific gravity
than the organic lubricants. Therefore, the oxide particles are less affected by the
flow of air in a powder bed during fluidization as compared to the organic lubricants.
In an iron-based mixed powder according to the present invention, presumably, an organic
lubricant is entirely or partially replaced with the oxide particles and therefore
the segregation of various additives is prevented. This probably results in the improvement
of the flowability of the iron-based mixed powder.
In the present invention, when the oxide particles have a large size, the oxide particles
do not cover the surface of the iron-based powder unlike a flowability-improving powder,
disclosed in Patent Literature 2, containing primary particles with a size on the
order of nanometers but are probably filled in voids in the iron-based powder in a
preferred manner. Thus, in a forming step presumably, the effective contact area between
a green compact and a die is increased and therefore the springback stress is distributed.
This probably results in a reduction in ejection force.
[0019] In order to exhibit the above effect, the oxide particles need to have an average
size of 0.5 µm or more. When the average size of the oxide particles is less than
0.5 µm, the effect of reducing ejection force cannot be sufficiently obtained. However,
when the average size of the oxide particles is more than 100 µm, the oxide particles
cannot be uniformly mixed with iron-based mixed powders (an average size of about
100 µm) usually used in powder metallurgy and therefore cannot exhibit the above effect.
Thus, the average size of the oxide particles is preferably 100 µm or less. The average
size of the oxide particles is more preferably 40 µm or less and further more preferably
20 µm or less. The average size of the oxide particles is preferably determined by
a method described in Example 1.
The oxide particles may contain about 20% by mass or less (the percentage with respect
to the oxide particles) of an impurity other than the oxide. Those having lower impurity
content (for example, 10% by mass or less or 2% by mass or less) are preferably used
if the commercial availability thereof is not difficult. The impurity is not particularly
limited and any impurity (for example, a metal or another inorganic compound) contained
in oxide particles produced by a known commercial process is not particularly problematic.
[0020] In the present invention, particles containing an oxide containing at least one selected
from the group consisting of iron, aluminum, and silicon are particularly advantageous
and are appropriate to the oxide particles. Examples of the oxide include Fe
2O
3, Al
2O
3, and SiO
2 and are not particularly limited in component or crystal structure. The content of
an oxide of at least one selected from the group consisting of iron, aluminum, and
silicon in the oxide particles is preferably about 80% by mass or more (the percentage
with respect to the oxide) and more preferably 98% or more in total.
[0021] In order to carry out the present invention at low cost, a particulate oxide satisfying
the above is preferably readily available at low cost. In view of availability, an
oxide of iron or an iron-based oxide containing an oxide of iron as a major component
is particularly preferred. Commercially available examples of the iron-based oxide
include those containing about 70% to 95% by mass (the percentage with respect to
the oxide) of an oxide of iron and about 5% to 30% by mass of an oxide of Al and/or
an oxide of Si in total.
When the form of powder is viewed form the viewpoint of aspect ratio, particles with
high aspect ratio can be artificially synthesized. For example, Patent Literature
4 discloses a method for synthesizing α-iron oxide with an aspect ratio of 5 to 30.
However, this method requires heating and pressurizing for a long time in the course
of synthesis, is irreversibly high in production cost, and also is not readily available.
Thus, the aspect ratio is preferably less than 5.
In the present invention, the aspect ratio refers to the ratio of the thickness to
the longitudinal size of powder as shown in Fig. 1. The aspect ratio of the oxide
particles is preferably determined by a method described in Example 1.
[0022] In the present invention, when the content of the oxide particles in the iron-based
mixed powder is less than 0.01% by mass, the effect of adding the oxide particles
is not obtained. However, when the content thereof is more than 5.0% by mass, an extreme
increase in ejection force is caused, which is not preferred. Thus, the content of
the oxide particles is 0.01% to 5.0% by mass.
The lower limit is preferably 0.05% by mass. The upper limit is preferably 1.0% by
mass.
[0023] In the present invention, the following powders are examples of the iron-based powder,
which is a major component of the iron-based mixed powder: pure iron powders such
as atomized iron powders and reduced iron powders, diffusion alloyed steel powders,
prealloyed steel powders, and hybrid steel powders produced by diffusion alloy components
in prealloyed steel powders. The iron-based powder preferably has an average particle
size of 1 µm or more and more preferably about 10 µm to 200 µm. The term "major component"
as used herein means that the content of the iron-based powder in the iron-based mixed
powder is 50% by mass or more.
[0024] Examples of powder for an alloy include graphite powders; powders of metals such
as Cu, Mo, and Ni; and metal compound powders. Other known powders for alloys also
can be used. The strength of a sintered body can be increased by mixing the iron-based
powder with at least one of these powders for alloys.
The sum of the contents of these powders for alloys in the iron-based mixed powder
is preferably about 0.1% to 10% by mass. This is because when the content of these
powders for alloys is 0.1% by mass or more or more than 10% by mass, the strength
of an obtained sintered body is advantageously increased or the dimensional accuracy
of the sintered body is reduced, respectively.
[0025] The powder for an alloy is preferably in such a state (hereinafter referred to as
an iron powder with alloy component adhered thereon) that the powder for an alloy
is attached to the iron-based powder with an organic binder therebetween. This prevents
the segregation of the powder for an alloy and allows components in powder to be uniformly
distributed therein.
[0026] Herein, an aliphatic amide, a metallic soap, or the like is particularly advantageous
and appropriate to the organic binder. Other known organic binders such as polyolefins,
polyesters, (meth) acrylic polymers, and vinyl acetate polymers can be used. These
organic binders may be used alone or in combination. In the case of using two or more
the organic binders, at least a part of the organic binders may be used in the form
of a composite melt. When the content of the organic binder is less than 0.01% by
mass, the powder for an alloy cannot be uniformly or sufficiently attached to iron
powders. However, when the content thereof is more than 1.0% by mass, the iron powders
adhere to each other to aggregate and therefore flowability may possibly be reduced.
Thus, the content of the organic binder preferably ranges from 0.01% to 1.0% by mass.
The content (mass percent) of the organic binder refers to the percentage of the organic
binder in the iron-based mixed powder for powder metallurgy.
[0027] In order to improve the flowability and formability of the iron-based mixed powder
for powder metallurgy, a free lubricant (powder) may be added thereto. The content
of the free lubricant in the iron-based mixed powder for powder metallurgy is preferably
1.0% by mass or less. On the other hand, the content of the free lubricant is preferably
0.01% by mass or more (the percentage with respect to the iron-based mixed powder).
The free lubricant is preferably a metallic soap (for example, zinc stearate, manganese
stearate, lithium stearate, or the like), a bis amide (for example, ethylene bis-stearamide
or the like), an aliphatic amide (for example, monostearamide, erucamide, or the like)
including an monoamide, an aliphatic acid (for example, oleic acid, stearic acid,
or the like), a thermoplastic resin (for example, an polyamide, polyethylene, polyacetal,
or the like), which has the effect of reducing the ejection force of a green compact.
A known free lubricant other than the above free lubricant can be used.
[0028] In the present invention, the content of the organic lubricant is less than ever
and the organic lubricant is replaced with the oxide particles, whereby flowability
and green density can be improved while excellent ejection force is maintained. That
is, the reduction in content of the organic lubricant usually degrades ejection force;
however, in the present invention, this adverse effect can be avoided by the addition
of the oxide. The use of the oxide instead of the organic lubricant improves green
density. Furthermore, the presence of the oxide particles improves fluidity. In order
to obtain the above advantages, the content of the organic lubricant in the iron-based
mixed powder is preferably 0.8% by mass or less, more preferably 0.7% by mass or less,
and further more preferably 0.6% by mass or less. The lower limit of the content of
the organic lubricant is preferably 0.02% by mass, which is the sum of the lower limit
of the content of the organic binder and that of the free lubricant.
The organic lubricant contains at least one of the organic binder, an organic free
lubricant, and an organic non-free lubricant (an organic lubricant attached to an
iron powder with a binder therebetween). The organic non-free lubricant is frequently
substituted by that of the organic binder in view or the function thereof. Therefore,
the sum of the content of the organic binder and that of the organic free lubricant
corresponds to the content of the organic lubricant.
The content of iron in the iron-based mixed powder is preferably 50% by mass or more.
[0029] A method for producing the iron-based mixed powder according to the present invention
is described below.
The iron-based powder is mixed with the oxide particles according to the present invention
and additives such as a binder and a lubricant and is further mixed with powder for
an alloy as required. The additives, such as the binder and the lubricant, need not
be necessarily added to the iron-based powder at once. After primary mixing is performed
using a portion of additives, secondary mixing may be performed using the rest thereof.
[0030] A mixing method is not particularly limited. Any conventionally known mixer can be
used. The following mixer can be used: for example, an impeller-type mixer (for example,
a Henschel mixer or the like) or a rotary mixer (for example, a V-type mixer, a double-cone
mixer, or the like), which is conventional known. When heating is necessary, the following
mixer is particularly advantageous and appropriate: a high-speed mixer, a disk pelletizer,
a plough share mixer, a conical mixer, or the like, which is suitable for heating.
[0031] In the present invention, an additive for property improvement may be used in addition
to the above additives according to purpose. For example, the addition of a powder
of MnS or the like for machinability improvement is exemplified for the purpose of
improving the machinability of a sintered body.
[EXAMPLES]
[EXAMPLE 1]
[0032] Prepared iron-based powders were two types: Pure Iron Powder A (an atomized iron
powder with an average particle size of 80 µm) and iron powder with alloy component
adhered thereon B prepared by attaching powders for alloys to this pure iron powder
with organic binders therebetween. The powders, for alloys, used for B were 2.0% by
mass of a Cu powder (an average particle size of 25 µm) and 0.8% by mass of a graphite
powder (an average particle size of 5.0 µm). The organic binders used were 0.05% by
mass of monostearamide and 0.05% by mass of ethylene bis-stearamide. The percentage
of each of these additives is a proportion to iron-based mixed powder.
[0033] Pure Iron Powder A and iron powder with alloy component adhered thereon B were mixed
with oxide particles with an aspect ratio of less than 5 and free lubricants at various
ratios, whereby iron-based mixed powders for powder metallurgy were obtained. The
oxide particles used were JC (TM) (Fe
2O
3 produced by JFE Chemical Corporation), MIOX (TM) (an Fe
2O
3-SiO
2-Al
2O
3 mixture, containing 90% by mass of Fe
2O
3, 5% by mass of SiO
2, and 3% by mass of Al
2O
3, the remainder being impurities (each is an approximate value), produced by Karntner
Montanindustrie Gesellschaft mbH), and A31 (TM) (Al
2O
3 produced by Nippon Light Metal Company, Ltd.). The free lubricants used were zinc
stearate, ethylene bis-stearamide, and erucamide in addition to 0.1% by mass of lithium
stearate. The iron powders and the oxide particles were measured for average particle
size by a laser diffraction/scattering method (according to JIS R 1629) and the particle
size at 50% in the particle size distribution (the cumulative volume fraction) was
used. The oxide particles were observed with a scanning electron microscope. The average
of the aspect ratios of randomly selected 50 particles was used as the aspect ratio.
The blending ratio of these mixed powders is shown in Table 1. The blending ratio
is a proportion to each iron-based mixed powder for powder metallurgy. For Pure Iron
Powder A, the content (mass percent) of an organic lubricant is equal to the content
of a free lubricant shown in Table 2. For iron powder with alloy component adhered
thereon B, the content thereof is equal to the sum of the content (0.1% by mass) of
an organic binder and the content of a free lubricant shown in Table 2.
[0034] Each obtained iron-based mixed powder was filled into a die and was then pressed
at room temperature with a pressure of 980 MPa, whereby a cylindrical green compact
with a diameter of 11 mm and a height of 11 mm was obtained. In this operation, the
flowability of the iron-based mixed powder, the ejection force needed to withdraw
the green compact from the die, and the density of the green compact were measured.
The measurement results are shown in Table 1. The flowability of the iron-based mixed
powder was evaluated in accordance with JIS Z 2502.
Herein, the flowability is good when the fluidity is not more than 30 seconds per
50 grams, the compressibility is good when the green density is 7.35 Mg/m
3 or more, and the drawability is good when the ejection force is 25 MPa or less.
[0035] [Table 1]
Table 1
No. |
Type of iron-based powder |
Oxide particles |
Free lubricant |
Properties |
Remarks |
Type |
Average particle size (µm) |
Aspect ratio |
Content (mass percent) |
Type |
Content (mass percent) |
Fluidity (sec/50 g) |
Green density (Mg/m3) |
Ejection force (MPa) |
1 |
B |
Iron oxide |
1.0 |
1 |
0.05 |
Zinc stearate |
0.4 |
23.9 |
7.38 |
17 |
Example 1 |
2 |
A |
Iron oxide |
1.0 |
1 |
1.0 |
Zinc stearate |
0.4 |
23.9 |
7.36 |
17 |
Example 2 |
3 |
B |
Fe2O3·SiO2·Al2O3 mixture |
0.8 |
2 |
0.2 |
Ethylene bis-stearamide |
0.1 |
21.0 |
7.42 |
18 |
Example 3 |
4 |
B |
Fe2O3·SiO2·Al2O3 mixture |
4.0 |
2 |
0.2 |
Ethylene bis-stearamide |
0.1 |
21.1 |
7.42 |
18 |
Example 4 |
5 |
B |
Fe2O3·SiO2·Al2O3 mixture |
18 |
3 |
0.2 |
Erucamide |
0.1 |
21.8 |
7.43 |
21 |
Example 5 |
6 |
B |
Fe2O3·SiO2·Al2O3 mixture |
38 |
4 |
0.2 |
Ethylene bis-stearamide |
0.1 |
21.3 |
7.42 |
22 |
Example 6 |
7 |
A |
Aluminum oxide |
5.0 |
1 |
0.1 |
Erucamide |
0.4 |
23.1 |
7.38 |
19 |
Example 7 |
8 |
B |
Aluminum oxide |
0.2 |
1 |
0.2 |
Erucamide |
0.4 |
Not flow |
7.33 |
16 |
Comparative Example 1 |
9 |
A |
Iron oxide |
0.08 |
1 |
0.2 |
Erucamide |
0.8 |
Not flow |
7.29 |
45 |
Comparative Example 2 |
10 |
B |
Iron oxide |
180 |
2 |
0.2 |
Erucamide |
0.8 |
Not flow |
7.29 |
45 |
Comparative Example 3 |
11 |
B |
Fe2O3·SiO2·Al2O3 mixture |
38 |
4 |
0.005 |
Erucamide |
0.3 |
Not flow |
7.31 |
25 |
Comparative Example 4 |
12 |
B |
Iron oxide |
20 |
1 |
6.0 |
Zinc stearate |
0.2 |
30.7 |
7.31 |
35 |
Comparative Example 5 |
*A: Pure iran powder, B: iron powder with alloy component adhered thereon |
[0036] As is clear from Table 1, an iron-based mixed powder excellent in flowability, compressibility,
and ejection force can be obtained by the addition of an appropriate amount of oxide
particles according to the present invention.
In contrast, comparative examples are poor in at least one of flowability, green density,
and ejection force.
[EXAMPLE 2]
[0037] A prepared iron-based powder was the same as iron powder with alloy component adhered
thereon B described in Example 1. The iron-based powder was mixed with oxide particles
(an aspect ratio of less than 5) and free lubricants as shown in Table 2, whereby
iron-based mixed powders for powder metallurgy were obtained. The oxide particles
used were similar to the commercial products described in Example 1. The percentage
of each additive shown in Table 2 is a proportion to corresponding iron-based mixed
powder. The flowability of each iron-based mixed powder, the ejection force needed
to withdraw a green compact (obtained from the iron-based mixed powder) from the die,
and the density of the green compact were measured in the same manner as that described
in Example 1. The measurement results are summarized in Table 2.
[0038] [Table 2]
Table 2
No. |
Content of binder mass percent |
Free lubricant |
Content of organic lubricant mass percent |
Oxide powder |
Properties |
Remarks |
Type |
Content mass percent |
Type |
Average particle size (µm) |
Aspect ratio |
Content mass percent |
Fluidity sec/50 g |
Green density Mg/m3 |
Ejection force MPa |
13 |
0.1 |
Ethylene bis-stearamide |
0.1 |
0.20 |
Fe2O3·SiO2·Al2O3 mixture |
4 |
2 |
0.05 |
24.6 |
7.41 |
20 |
Example |
14 |
0.1 |
Ethylene bis-stearamide |
0.3 |
0.40 |
Fe2O3·SiO2·Al2O3 mixture |
4 |
2 |
0.2 |
23.8 |
7.43 |
19 |
Example |
15 |
0.1 |
Ethylene bis-stearamide |
0.4 |
0.50 |
Fe2O3·SiO2·Al2O3 mixture |
4 |
2 |
0.2 |
24.2 |
7.42 |
19 |
Example |
16 |
0.1 |
Ethylene bis-stearamide |
0.7 |
0.80 |
Fe2O3·SiO2·Al2O3 mixture |
4 |
2 |
0.2 |
29.0 |
7.35 |
15 |
Example |
17 |
0.1 |
Ethylene bis-stearamide |
0.1 |
0.20 |
Not used |
- |
- |
- |
28.2 |
7.34 |
35 |
Comparative Example |
18 |
0.1 |
Ethylene bis-stearamide |
0.4 |
0.50 |
Not used |
- |
- |
- |
Not flow |
7.33 |
22 |
Comparative Example |
19 |
0.1 |
Ethylene bis-stearamide |
0.5 |
0.60 |
Not used |
- |
- |
- |
Not flow |
7.30 |
20 |
Comparative Example |
20 |
0.1 |
Ethylene bis-stearamide |
0.7 |
0.80 |
Not used |
- |
- |
- |
Not flow |
7.27 |
18 |
Comparative Example |
21 |
0.1 |
Ethylene bis-stearamide |
0.2 |
0.30 |
Iron oxide |
1 |
1 |
0.2 |
24.2 |
7.41 |
16 |
Example |
22 |
0.1 |
Ethylene bis-stearamide |
0.4 |
0.50 |
Aluminum oxide |
5 |
1 |
0.2 |
24.6 |
7.42 |
15 5 |
Example |
[0039] Table 2 shows that iron-based mixed powders (Nos. 14 and 15) which contain iron oxide
particles (particles of an Fe
2O
3-SiO
2-Al
2O
3 mixture) and which have a reduced organic lubricant content of 0.4% to 0.5% by mass
have substantially equal ejection force and also have significantly improved green
density and flowability as compared to, for example, an iron-based mixed powder (No.
20) containing 0.8% by mass of an organic lubricant. As is clear from No. 13, good
flowability, green density, and ejection force can be obtained even though an organic
lubricant is further reduced.
In the case of changing an organic binder, a free lubricant, powder for an alloy,
and/or oxide particles (in particular, oxide particles containing iron, aluminum,
and/or silicon) or in the case of adding powder for machinability improvement, substantially
the same results as those described in Example 1 or 2 were obtained.
Industrial Applicability
[0040] Not only flowability but also green density and ejection force can be improved by
adding an appropriate amount of oxide particles according to the present invention
to an iron-based powder. Therefore, production efficiency can be increased and production
costs can be reduced.
Reference Signs List
[0041]
- 1 longitudinal size
- 2 thickness