JP2003030816A - Substrate for information recording medium, information recording medium and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass substrate containing alkali metals (a substrate for an information recording medium) which suppresses alkali elution during forming, which has excellent durability after manufactured, which can be easily produced at a low cost and which has excellent performances necessary for the substrate of a magnetic recording medium, to provide an information recording medium which uses the above substrate for an information recording medium, and to provide a method for manufacturing the same. SOLUTION: The glass material contains composition components of B2 O3 , Al2 O3 and R2 O (R represents alkali metals) controlled to satisfy, in terms of the molar ratio, 0.8<=(addition amount of R2 O-addition amount of Al2 O3 )/ addition amount of B2 O3 <=1.2, 9.0 mol%<=addition amount of B2 O3 <=14.0 mol% and 3.0 mol%<=addition amount of Al2 O3 <=7.0 mol%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium substrate made of an alkali metal-containing glass substrate and an information magnetic recording medium using the information recording medium substrate.

[0002]

2. Description of the Related Art With the recent trend toward higher density recording of magnetic disks, not only is the performance of the magnetic layer for recording digital signals improved, but also various constituent elements such as a magnetic head for reading and writing the recording and a substrate for the magnetic disk. Performance improvement is also required. In consideration of such requirements, as a substrate, a glass substrate has been attracting attention instead of an aluminum substrate which has been conventionally used.

The reason why the glass substrate has begun to attract attention as the substrate of the magnetic disk is that (i) it is easy to thin the substrate required for miniaturization and high density of the magnetic disk by using a glass material. , (Ii) It is easy to secure the flatness of the substrate surface that enables a low flying height of the magnetic head, and (iii) In addition, the glass substrate has higher potential than the aluminum substrate. It has. In addition, since a glass material can be easily formed into a disc shape by applying pressure at a softening temperature or higher, it is possible to produce a disc-shaped substrate using glass at low cost. Having it is one of the reasons.

Considering the cost reduction in manufacturing such a glass substrate, it is necessary not to shorten the life of the pressurizing device and the mold used for molding the substrate. It is desirable that the temperature is as low as possible.

Generally, in order to lower the molding temperature of the glass substrate, an alkali metal such as Li, Na or K is added to the glass raw material. However, on the other hand, addition of an alkali metal to the glass substrate corrodes the magnetic layer of the information magnetic recording medium or deteriorates the surface lubricating layer,
It is also known that there is a big demerit that surface deposits are generated and the head is destroyed. Thus, from the viewpoint of using the glass material as the substrate material for the information magnetic recording medium, it is desired to suppress the elution of alkali metal ions as much as possible.

On the other hand, as a method for preventing the elution of alkali metal ions from glass to which an alkali metal such as Li, Na or K has been added, some methods have been proposed so far. The main ones are the following methods.

(1) A tetravalent oxide such as ZrO ₂ or SnO ₂ is added.

(2) Add a rare earth oxide such as La ₂ O ₃ or Gd ₂ O ₃ .

[0009]

However, in both the above methods (1) and (2), the glass softening temperature (Ts) increases when the amount of oxides added is increased in order to suppress the elution of alkali metals. Will rise by several tens of degrees Celsius. As is well known, since Ts is almost proportional to the molding temperature,
When Ts rises by several tens of degrees Celsius, the molding temperature inevitably increases by several tens
However, even if the alkali elution can be suppressed, the purpose of lowering the original molding temperature cannot be fulfilled. That is, by the addition of the oxide, the glass molding temperature rises, and accordingly, the life of the substrate molding die is shortened, and the molding tact time is lengthened.
The harmful effect comes out. In order to lower the molding temperature, it is necessary to add an alkali metal, which only leads to a vicious cycle in manufacturing a glass substrate. As described above, the conventional glass substrate manufacturing technology has not been able to improve the trade-off relationship between low temperature molding and low alkali elution.

Therefore, the object of the present invention is to suppress the amount of alkali elution at the time of molding, to have excellent durability after production, and to provide it easily and inexpensively, which is required for a substrate of a magnetic recording medium. It is an object of the present invention to provide an alkali metal-containing glass substrate (substrate for information recording medium) excellent in excellent performance, an information magnetic recording medium using the substrate for information recording medium, and a manufacturing method thereof.

[0011]

Means for Solving the Problems The present inventors have made various studies on alkali elution from a conventional alkali metal-containing glass substrate (hereinafter, also simply referred to as a glass substrate), and as a result, have obtained the following findings. Obtained.

That is, the conventional method (1) described above,
Even if an additive such as (2) that significantly increases the glass softening temperature is not used, B ₂ O ₃ , Al ₂ O ₃ , R ₂ O (R ₂ O ₃ Is
It has been found that if the addition ratio of (alkali metal such as Li, Na, K) is controlled within a specific range with high accuracy, the amount of alkali elution can be significantly reduced as compared with the conventional glass substrate without increasing Ts. The present invention has been completed.

The information recording medium substrate according to the present invention has a composition
At least B per minute_TwoO_Three, Al_TwoO _Three, R_TwoO (R is a
Lucari metal), these components are
Relational expressions (I), (II), (III); Relational expression (I) 0.8 ≦ (R_TwoO addition amount-Al_TwoO_ThreeAttendant
Addition) / B_TwoO_ThreeAddition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B_TwoO_ThreeAddition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≦ Al_TwoO_ThreeAddition amount ≤
7.0 mol% Molded glass material containing alkali metal
It is characterized by

The R ₂ O addition amount is inevitably derived from the above relational expressions (I), (II) and (III), and the value is 10.2 mol% ≤ R ₂ O addition amount ≤ It becomes 23.8 mol% (relational formula (IV)).

By controlling the glass material of the substrate in the above component composition, the substrate for information recording medium of the present application is
The amount of alkali elution can be significantly reduced as compared with the conventional substrate without increasing Ts.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first aspect of the present invention relates to a substrate for information recording medium. The information recording medium substrate according to the present invention has at least B ₂ O ₃ , Al ₂ O ₃ , and R _{2 in the} composition.
O (R is an alkali metal), and these components are, in molar ratio conversion, the following relational expressions (I), (II), and (III); Relational expression (I) 0.8 ≦ (R ₂ O addition amount -Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
It is characterized in that it is formed by molding an alkali metal-containing glass material satisfying 7.0 mol%.

A second aspect of the present invention is a base for an information recording medium.
The present invention relates to a method for manufacturing a plate. For information recording medium according to the present invention
The method of manufacturing the substrate is such that at least B is added to the composition._TwoO_Three, Al
_TwoO _Three, R_TwoO (R is an alkali metal)
The following relational expressions (I), (II), (II
I); Relational expression (I) 0.8 ≦ (R_TwoO addition amount-Al_TwoO_ThreeAttendant
Addition) / B_TwoO_ThreeAddition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B_TwoO_ThreeAddition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≦ Al_TwoO_ThreeAddition amount ≤
7.0 mol% Alkali metal-containing glass material satisfying
It is special to mold the glass material of
To collect.

FIG. 1 is a schematic view for explaining an example of an information recording medium substrate according to the present invention. As can be seen from FIG. 1, the information recording medium substrate 1 is composed of a disk-shaped alkali metal-containing glass substrate 3 having a circular hole 2 formed in the center thereof.

As an example, the alkali metal-containing substrate 3 is manufactured by the following procedure. First, glass powder containing an additive having a desired composition is melted to prepare a disk-shaped glass having a weight of about 6 g, a thickness of about 8 mm and a diameter of about 23 mm. Next, a disk-shaped glass is molded near Ts,
The disk-shaped glass substrate has a thickness of 0.635 mm and a diameter of 65 mm. Then, an inner diameter of 20
mm mm holes are made and general chemical strengthening is performed to further increase the mechanical strength of the substrate. This chemical strengthening is N
aNO ₃ and KNO ₃ are mixed at a ratio of 0.4 to 0.6, and the mixture is maintained at 350 to 400 ° C.
By immersing the glass substrate for 5 hours,
Be implemented. Finally, the glass substrate is washed in pure water, and further, scrub cleaning, pure water drop cleaning, and isobromopyr alcohol (IPA) cleaning are performed.

A third aspect of the present invention relates to an information magnetic recording medium provided with the information recording medium substrate 1 shown in the first aspect of the present invention. That is, as shown in FIG. 2, the information magnetic recording medium according to the present invention has an information recording medium substrate 1 made of an alkali metal-containing glass substrate 3 and a magnetic layer 4 laminated on the substrate 1. The information recording medium substrate 1 contains at least B ₂ O ₃ and Al in the composition.
₂ O ₃ , R ₂ O (R is an alkali metal), and these components are represented by the following relational formulas (I), (II), (II
I); Relational expression (I) 0.8 ≦ (R ₂ O addition amount−Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational expression (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
It is characterized in that it is formed by molding an alkali metal-containing glass material satisfying 7.0 mol%.

A fourth aspect of the present invention is the same as the third aspect.
The present invention relates to a method for manufacturing an information recording medium. Information based on the present invention
The recording medium manufacturing method is such that at least B is added to the composition._TwoO_Three,
Al _TwoO_Three, R_TwoHas O (R is an alkali metal), which
The following relational expressions (I), (II),
(III); Relational expression (I) 0.8 ≦ (R_TwoO addition amount-Al_TwoO_ThreeAttendant
Addition) / B_TwoO_ThreeAddition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B_TwoO_ThreeAddition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≦ Al_TwoO_ThreeAddition amount ≤
7.0 mol% Alkali metal-containing glass material satisfying
The glass material of was molded into a substrate for information recording media and molded
It is characterized in that a magnetic recording layer is laminated on a substrate.

The information recording medium of the present invention is characterized in that the alkali metal-containing glass substrate is composed of a glass composition satisfying the above-mentioned relational expression, so that the amount of alkali elution from the substrate is small. The information magnetic recording medium configured as described above may further include an underlayer, a protective layer, a lubricating layer, and the like, if necessary.

In order to achieve a high performance information magnetic recording medium, it is preferable to provide an underlayer on the substrate to control the orientation of the magnetic layer.

As described above, according to the present invention, when the alkali metal-containing glass substrate is composed of the composition satisfying the above relational expression, the elution of alkali from the substrate for information recording medium is suppressed and the elution is suppressed. It is possible to prevent the information magnetic recording medium from being corroded, deteriorated, or destroyed by the alkali. As a result, it is possible to provide an information magnetic recording medium having excellent durability and high reliability. It will be easily understood by those skilled in the art that the structure and shape of the information magnetic recording medium are not particularly limited and can be variously modified.

[0025]

EXAMPLES The present invention will be described in more detail with reference to examples below, but these do not limit the present invention.
It goes without saying that various modifications can be made without departing from the scope of the present invention.

(Production of Alkali Metal-Containing Glass Substrate) The alkali metal-containing glass substrate used in the following examples was produced as follows.

SiO having the composition shown in Table 1_Two, B_TwoO_Three, A
l_TwoO_Three, Li_TwoO, Na_TwoO, K _TwoWeigh O powder
After mixing, put in a crucible and melt at 1400 to 1500 ° C
It was This melted glass is removed from the crucible
Pour into a carbon carbon mold, weigh about 6g, thickness about 8
mm glass with a diameter of approximately 23 mm (hereinafter referred to as "mar
I will call it "Bull"). Then this mar
Introduce the bull into the mold for molding before it cools sufficiently,
0.2 ~ 0.6t while keeping the mold at a temperature near Ts
/ Cm²Pressurized for 3 minutes.
Disk-shaped glass with a diameter of 65 mm and a thickness of 0.635 mm
I got a plate. Next, at the center of this glass plate, the diameter is 20 m.
M holes are provided to further secure the bending strength of this disc.
Therefore, chemical strengthening was applied.

The specific treatment conditions for the chemical strengthening are as follows: The nitrate mixed at a weight ratio of NaO ₃ : KNO ₃ = 2: 3 was melted at 370 ° C., and the melt was perforated. The glass plate was immersed for 2 hours.

Finally, the glass substrate after the chemical strengthening was washed and dried.

Σ R ₂ O shown in Table 1 is Li
₂ O, Na ₂ O, and K ₂ O are shown in total, and Rf
Is a value represented by the following formula.

Rf = (ΣR ₂ O-Al ₂ O ₃ addition amount)
/ _B 2 _{O 3} addition amount (unit: mol%)

(Evaluation of Alkali Elution Amount) In the following Examples, in order to evaluate the effect of preventing alkali elution, the amount of alkali elution from the glass substrate was analyzed according to the following procedure.

(A) 10 mL of pure water is placed in a Teflon (registered trademark) container with a lid having a volume of 0.5 L, and one substrate to be evaluated is further placed.

(B) This container is placed in a thermostat at 80 ° C. and left for 24 hours.

(C) The Teflon (registered trademark) container was taken out from the constant temperature bath, pure water was collected, and the alkaline element eluted in the pure water was examined by ICP analysis.

(D) The total alkali elution amount per unit area was calculated from the obtained ICP analysis value.

(Example 1) In this example, an alkali metal-containing glass substrate having the composition shown in Table 1 and Table 1 (continuation) was produced by the above-mentioned method. The elution amount was evaluated.
The results are shown in Table 1 and Table 1 (continuation). In the judgment column in the table, ○ and ● indicate the judgment results, and ○ indicates that Ts is 650 ° C. or less and the amount of alkali elution is 5.0 m.
g / m ² or less, and ● indicates Ts greater than 650 ° C. or alkali elution amount greater than 5.0 mg / m ² . Here, the amount of Li ₂ O added: the amount of Na ₂ O added: the amount of K ₂ O added = 10: 6: 1 is fixed.

As a reference sample, the glass compositions that have been studied conventionally are also shown in Table 1 as Reference # 1 and Reference # 2. Reference # 1 is a substrate having a low Ts of 590 ° C. but a large alkali elution amount of 11.7 mg / m ₂ , whereas Reference # 2 has a alkali elution amount of 5.0 mg / m 2.
_Although it is as small as ₂ , the glass substrate has a defect that the life of the molding die is short because Ts is as high as 670 ° C. In general,
As in References # 1 and # 2, there is a trade-off relationship between the alkali elution amount and Ts.

On the other hand, in the present invention, Al_TwoO_ThreeBut
When it is 3.0 to 7.0 mol%, B _TwoO_ThreeIs 9.0-1
4.0 mol% and Rf in the range of 0.8 to 1.2
If Ts is 650 ° C or less,
5.0 mg / m^TwoBelow, i.e.
It

When the added amount of B ₂ O ₃ exceeds 15 mol%, the alkali elution amount increases because the added amount of B ₂ O ₃ increases and B ₂ O ₃ evaporates from the glass during melting. It is presumed that this is because the marble surface partially causes compositional deviation.

(Example 2) In Example 1 described above, Rf
Is 0.8 to 1.2, and the amount of B ₂ O ₃ added is 9.0 to 1
It has been described that the present invention is established when the content is 4.0 mol%. In Example 2, the effective range of Al ₂ O ₃ will also be described.

The preparation method of the sample is the same as that of the example 1, and the combination shown in Table 2 was used for the experiment. The judgment criteria are also the same. Here, Rf is fixed to 1, which is the central value of the present invention. As is clear from Table 2, the added amount of Al ₂ O ₃ is within the range shown in Table 1, 3.0 to 7.0 mol%.
If it exceeds 2 mol% or 8 mol%, Rf = 1
However, the judgment is ●.

Therefore, combining the results of Example 1 and Example 2, the addition range of Al ₂ O ₃ is 3.0 to
It is limited to 7.0 mol%.

Although not shown here, K
_In the case of adding an alkali ion metal having a large ionic radius such as ₂ O, Rb ₂ O and Cs ₂ O, too much addition is not preferable in order to effectively act on the above-mentioned chemical strengthening, and about 1.5 The mol% is the limit.

From the above Examples 1 and 2, it was revealed that the information recording medium substrate according to the present invention is excellent in suppressing alkali elution. Therefore, next, an information magnetic recording medium using the information recording medium substrate according to the present invention was examined.

(Embodiment 3) This embodiment relates to an information magnetic recording medium constituted by using an information recording medium substrate according to the present invention. Using the various substrates produced in Example 1,
Information magnetic recording media were manufactured as follows.

No. 1 produced in Example 1 An information magnetic recording medium was manufactured by sequentially stacking a Cr underlayer, a CoPtCr magnetic layer, and a C protective film on both surfaces of the No. 38 information recording medium substrate. In order to examine the weather resistance of the obtained information magnetic recording medium, after leaving it in an atmosphere of 80 ° C. and 85% RH for 1000 hours, a surface condition of the substrate and a flying height test of the magnetic recording medium were carried out. The result is N in Table 3
o. 82.

As a reference sample, a reference # 1 substrate shown in Table 1 was similarly prepared, and the weather resistance was examined by the same procedure. The results are shown in Table 3, No. 83.

As can be seen from Table 3, in the glass substrate of Reference # 1, deposits having a dendrite structure with a size of several tens of μm, which consist of a mixed carbonate of lithium and sodium, were recognized on the surface. For this reason, recording cannot be read / written.

On the other hand, No. 1 produced according to the present invention. Three
No precipitation of alkali carbonate was observed on the 8 glass substrate, and no change in the flying height was observed. In addition, the magnetic properties were almost the same as in the initial stage.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

As described above, when a glass substrate for an information recording medium containing alkali ions which enables low temperature molding is produced, a glass having a composition satisfying the following relational expressions (I) to (III) By making a substrate from the above, it becomes possible to provide a substrate for an information recording medium with little alkali elution.

Relational expression (I) 0.8 ≦ (R ₂ O addition amount−
Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
7.0 mol% (Note that the R ₂ O addition amount is inevitably derived from the above relational expressions (I) to (III), and 10.2 mol% ≤ R ₂ O addition amount ≤ 2
It becomes 3.8 mol%. Further, by manufacturing an information recording medium using a glass substrate having such a composition, 80 ° C. and 85% RH can be obtained.
Even in such a severe weather resistance test as described above, it is possible to provide an information magnetic recording medium exhibiting magnetic characteristics that are the same as those in the initial period for 1000 hours.

As described above, according to the present invention, an inexpensive information recording medium substrate satisfying contradictory characteristics such as low temperature processability and high weather resistance, and an information magnetic recording medium using the information recording medium substrate, It becomes possible to provide the manufacturing method for them.

[Brief description of drawings]

FIG. 1 is a schematic plan view for explaining an example of an information recording medium substrate according to the present invention.

FIG. 2 is a schematic cross-sectional stack diagram for explaining an example of the information recording medium according to the present invention.

[Explanation of symbols]

1 Information recording medium substrate 2 holes 3 Glass substrate containing alkali metal 4 Magnetic layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryoji Kobayashi             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Takahiro Tokuyo             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Kunio Hibino             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Minoru Onoda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 4G062 AA01 BB01 CC10 DA06 DA07                       DB03 DC03 DC04 DD01 DE01                       DF01 EA01 EA02 EA03 EA04                       EA10 EB01 EB02 EB03 EB04                       EC01 EC02 EC03 ED01 EE01                       EF01 EG01 FA01 FA10 FB01                       FC01 FD01 FE01 FF01 FG01                       FH01 FJ01 FK01 FL01 GA01                       GA10 GB01 GC01 GD01 GE01                       HH01 HH02 HH03 HH05 HH07                       HH09 HH11 HH13 HH15 HH17                       HH20 JJ01 JJ03 JJ05 JJ07                       JJ10 KK01 KK03 KK05 KK07                       KK10 MM27 NN34                 5D006 CB06                 5D112 AA02 BA03 BA07

Claims (4)

[Claims] 1. A substrate for an information recording medium, comprising at least B ₂ O ₃ , Al ₂ O ₃ , R ₂ O (R
Is an alkali metal), and these components have the following relational formulas (I), (II) and (III) in terms of molar ratio; relational formula (I) 0.8 ≦ (R ₂ O addition amount−Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
A substrate for an information recording medium, which is formed by molding an alkali metal-containing glass material satisfying 7.0 mol%. 2. A method for manufacturing an information recording medium substrate, comprising at least B ₂ O ₃ , Al ₂ O ₃ and R ₂ O (R
Is an alkali metal), and these components are converted into molar ratios in the following relational expressions (I), (II) and (III); relational expression (I) 0.8 ≦ (R ₂ O addition amount−Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational formula (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
A method for producing a substrate for an information recording medium, which comprises preparing an alkali metal-containing glass material satisfying 7.0 mol% and molding the glass material into a substrate for an information recording medium. 3. An information recording medium comprising an information recording medium substrate and a magnetic layer laminated on the substrate, wherein the information recording medium substrate has at least B ₂ O in its composition.
₃ , Al ₂ O ₃ , R ₂ O (R is an alkali metal),
These components have the following relational expressions (I) and (I
I), (III); Relational expression (I) 0.8 ≦ (R ₂ O addition amount−Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational expression (II) 9.0 mol % ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
An information magnetic recording medium characterized by being formed by molding an alkali metal-containing glass material satisfying 7.0 mol%. 4. The composition contains at least B ₂ O ₃ , Al ₂ O.
₃ , R ₂ O (R is an alkali metal), and these components are represented by the following relational formulas (I), (II), (II
I); Relational expression (I) 0.8 ≦ (R ₂ O addition amount−Al ₂ O ₃ addition amount) / B ₂ O ₃ addition amount ≦ 1.2 Relational expression (II) 9.0 mol% ≦ B ₂ O ₃ addition amount ≦ 14.
0 mol% Relational formula (III) 3.0 mol% ≤ Al ₂ O ₃ addition amount ≤
An information recording medium, characterized in that an alkali metal-containing glass material satisfying 7.0 mol% is prepared, the glass material is molded into a substrate for information recording medium, and a magnetic recording layer is laminated on the molded substrate. Manufacturing method.