How to select standard bellows｜Products

How to select standard bellows

About standard products

Standard products can be used under respective standard specifications.

If you adopt standard products as and when conditions permit, they can be conveniently used in terms of delivery time and price.

Discrete welded bellows

Selection procedures

1. Check specification conditions to see whether standard products can be used.

Pressure conditions	(Internal) vacuum (External) atmospheric pressure
Temperature conditions	Ordinary temperature (baking temp. max. 250°C)
Operating conditions	Axial displacement only; at intervals of 10mm; up to maximum allowable displacement per block
Leak rate	1×10^-9 Pa・m³/s or less

2. Select bellows material

	Corrosion resistance	Compact	Lifetime characteristics	Softening of spring	Magnetism	Material price
SUS316L	○	○	○	◎	Non-magnetic	Low
AM350 equivalent	×	◎	◎	○	Magnetic	Higher than SUS

3. Select lifetime.
　　10,000 repetitions or 100,000 repetitions or 1,000,000 repetitions
　* If your specification life is not standard, move up one rank.
　* For exceeding 1,000,000 repetitions, custom design is required.

4. Check the bellows size.

　○ Interference check

　　- Check for interference with the shaft passing through the bellows.
A minimum clearance of 2mm is required on one side.

　　- Check for interference with the inner diameter of the externally interfering object outside the bellows.
A minimum clearance of 2mm is required on one side.

Model	Size	Model	Size
22	8×22	109	79×109
30	17×30	120	90×120
36	22×36	150A	100×150
51	36×51	150B	120×150
70	50×70	210	160×210
90	60×90	270	206×270
94	70×94	320	260×320

5. Upon determination of material, lifetime, expansion/contraction, and size, select a compatible model from the table.

　○Maximum stroke

　　- Select so that the required stroke falls within the allowable stroke.

　　- If the allowable stroke is exceeded, “air buckling,” “horizontal sagging,” or “vertical contact” may occur.

　○End fitting

　 - When fittings are welded by the user or fittings are supplied by the user,

　　　end fittings are Y-type (Y).

　　- When fittings are welded by us,

　　　corrugated type (E) is selectable, which will enable a more compact design than Y-type (Y).

6. Check the operating range to see whether use within the target operating range is possible.
　Note that the operating range of bellows should include end fitting lengths.

　Unrestricted length = Unrestricted length (list) × (required stroke/10) + end fitting × 2

　Maximum length = Maximum length (list) × (required stroke/10) + end fitting × 2

　Minimum length = Minimum length (list) × (required stroke/10) + end fitting × 2

7. Check the spring constant in the axial direction.

　Axial direction spring constant = Axial direction spring constant (list) / (required stroke/10)

For the model numbers of discrete welded bellows, click here.

For ordering discrete welded bellows, click here.

Flanged welded bellows, formed bellows, and flexible tubes

Selection procedures

For detailed numerical values, see each standard product.

1. Check to see whether the flange shape you want to use is available.

2. Consider bellows type.

Type	Expansion/contraction properties		Airtightness	Spring properties	Pressure resistance
Welded	◎		◎	Soft	◎
Formed	○		◎	Hard	○
Flexible	×		◎	×	×
Type	Bendability	Washability	Contamination	Mass producibility	Price
Welded	◎	△	△	○	○
Formed	○	○	○	◎	◎
Flexible	◎	○	○	○	◎

3. Check specification conditions to see whether standard products can be used.

4. Check the bellows size.

　○ Interference check (excluding flexible tubes)

　　- Check for interference with the shaft passing through the bellows.
　　　A minimum clearance of 2mm is required on one side.

　　- Check for interference with the inner diameter of the externally interfering object outside the bellows.
　　　A minimum clearance of 2mm is required on one side.

5. If bellows specifications are met, select a compatible model from the table.

6. For different lengths of formed bellows, specify the lengths.

For the model numbers of welded bellows with flanges,click here.

For the model numbers of formed bellows with flanges, click here.

For the model numbers of flexible tubes with flanges, click here.

For ordering standard bellows with flanges, click here.