Обший каталог Yamawa 2016 - 2017 - страница 797

12.12. How to set the tap's oversize to meet with the coating

margin of internal threads

1) Relation between coating thickness and pitch diameter when applied with coating

Dwg.1 shows the relation between coated internal thread and pitch diameter

* Thickness of coating is measured at right angle to flank face. Pitch diameter is measured at right angle to axis (radially).

Drawing 1

Coating thickness 3μm

half of pitch diameter

decrease (6μm)

Accuracy of roll tapsAccuracy of roll taps

ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X ISO 3XISO 3X ISO 2XISO 2X

88 1818 GS1GS1 2323 GS2GS2 2828

1010 2020 3030

S0.6×0.15S0.6×0.15 GS2GS2 S0.7×0.175S0.7×0.175 GS3GS3

S0.8×0.2S0.8×0.2 GS3GS3 S0.9×0.225S0.9×0.225 GS4GS4

Tap class for 6H ISO2XTap class for 6H ISO2X Tap class for 6G ISO3XTap class for 6G ISO3X Internal threads 6HInternal threads 6H

ISO 3XISO 3X

4040

4545

Where t (coating thickness) equals 3μm, by using following formula, oversize is roughly caluculated.

Pitch diameter decrease 2t×2 (both side of threads) = 3μm×2×2 =12 μm (rough over size)

2) How to specify taps for coating

1. We suppose the accuracy of finished internal threads is 6H class, and inspection is done with GP-6H and NP-6H. 2. We suppose the disperse of coating thickness is controlled within the tolerance of 8~16μm. The disperse of coating thickness, when it is exchanged into pitch diameter, will become the disperse of 32~64μm. 3. Accuracy of internal threads before coating is the thread accuracy which GP-6H goes through (OK), even when max coating (64μm) is applied. And this accuracy is the thread accuray which NP-6H does not go through (OK), when min coating (32μm) is applied. 4. We propose followings for inspecting the accuracy of internal threads before coating :

GO gauge before coating : GP-6H+64

5. Next, based on GO gauge before coating and NOT GO gauge before coating, we study to specify the suitable accuracy of the tap before coating.

M6×1 How to specify the accuracy of tap before coating (Coating thickness 8~16μm)

Pitch diameter of JIS 6H Pitch diameter of JIS 6H

GP-6H

NP-6H

Internal threads before coating Internal threads before coating

GP-6H+64 NP-6H+32 Suggested cutting taps

Suggested roll taps

(μm) Basic pitch diameter : 5.350mm M6×1 Basic pitch diameter : 5.350mm Internal thread tolerance 6H : 0~+150μm (Tolerance : 150μm)

Accuracy of suggested cutting taps (P5.5) : +90~+110μm Accuracy of suggested roll taps (G12) : +140~+152μm