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Catalogue Miniature Metal Bellows & Electroforms Brochure

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INTRODUCTION

INDEX

SERVOMETER® ELECTRODEPOSITED METALLIC BELLOWS

There are five major types of metal bellows: rolled, hydroformed, welded, chemically deposited and electro-deposited. Electro-deposited bellows are manufactured by forming a mandrel to the shape of the inside of the bellows, depositing the proper thickness of spring quality metal onto this, trimming tie ends and dissolving out the mandrel.

Servometer® is the foremost manufacturer of electro-deposited bellows. These bellows have the following advantages over other types.

1. Because the bellows wall can be thinner than other types (to .0002"), they are extremely sensitive, which makes them excellent for very accurate instrument applications requiring a high degree of sensitivity. They can provide large deflections with only very minute forces. They are up to 25 times as sensitive as hydroformed bellows in the same size range. Servometer® manufactures bellows which can be fully compressed by a force as small as 4 grams.

2. They are the most flexible bellows. They offer superb performance in applications such as hermetic sealing of switches and professional circuit breakers, and other filled instruments.

3. Their stroke can be 60% of their extended length, and combined with a greater I.D./O.D. ratio, this gives them a volume displacement capacity equal to or larger than most other types.

4. They can be designed for infinite life expectancy and have a normal minimum life of 100,000 cycles.

5. They are seamless and non-porous. No dust, dirt or moisture can lodge in seams and cause contamination in critical applications. In addition, every Servometer® bellows is leak tested to 10^-9 ccHe/sec. by helium manufacturers of mass spectrometer.

6. They can be made in sizes smaller than any other bellows. Many of today's sophisticated applications require a miniaturized bellows. Servometer^® bellows can be made as small as .020" O.D. and still retain full sensitivity and flexibility. When other types are smaller than 1/4" O.D., they are usually stiff and useless for most applications.

7. Tooling is not required for most bellows, so that a large quantity need not be ordered to attain a reasonable price.

TYPICAL APPLICATIONS OF BELLOWS 2

SERVOMETER® ELECTRODEPOSITED METAL BELLOWS 3

SECTION I - BELLOWS DESIGN

HOW TO ESTABLISH A BELLOWS DESIGN 4

ILLUSTRATION OF TYPE OF BELLOWS ENDS 4

SERVOMETER® STOCK BELLOWS 4

BELLOWS DESIGN REQUEST FORM 5

HOW TO USE THE TABLE OF BELLOWS 6

CONVOLUTION PROPERTIES

TABLE OF BELLOWS CONVOLUTION PROPERTIES 6

SECTION II - PROPERTIES OF SERVOMETER® BELLOWS

TOLERANCES 7

DESIGN LIMITS 7

METAL COMPOSITION 7

SURFACE FINISHES 7

LEAK TIGHTNESS 7

ENVIRONMENTAL TOLERANCES 7

JOINING OF BELLOWS TO END PROFESSIONAL FITTINGS 8

SPECIAL TYPES OF BELLOWS 8

HIGH COMPRESSION BELLOWS 8

MULTI-PLY BELLOWS 8

PRE-COMPRESSED BELLOWS 8

SECTION III - MATHEMATICAL DESIGN OF A BELLOWS

SYMBOLS 9

PRESSURE RATING 9

STROKE RATING 9

RATING BELLOWS FOR COMBINED STROKE AND PRESSURE 9

LIFE EXPECTANCY 9

DE-RATING BELLOWS STROKE FOR PRESSURE & LIFE 9

SPRING RATE 9

EFFECTIVE AREA 9

CRITICAL BUCKLING PRESSURE 10

ALLOWABLE CIRCULAR ARC BENDING 10

OFF-SET BENDING WITH ENDS PARALLEL 10

SERVOMETER® ELECTROFORMS

BENEFITS 10

DESIGN CONSIDERATION 11

ADVANTAGES 11

MATERIALS & PROPERTIES 11

SIZE LIMITATION 11

DESIGN ASSISTANCE 11

SERVOMETEFTS PROCESS OF ELECTRODEPOSITION

Machine Mandn

Electrodeposit Nick onto Mandrel

Trim Plated Mandrel

Dissolve Mandrel

Spring Rate Bellows To Check Wall