Methods of Assembly Flashcards
The method of assembling parts is determined by: (3)
- interference,
- equipment available,
- size of parts being assembled
when one part is pressed onto another, this is called:
Forced fitting
when the hub is heated/expanded to be assembled upon the shaft, this is called:
shrink fitting
when the shaft is cooled/shrunk to allow parts to be assembled upon it, this is called:
expansion fitting
This is the most accurate method of assembly of parts with an interference fit:
forced fitting
When performing a forced fitting, what two types of presses could you use? (2)
- Hydraulic press
- Arbor press
What two styles of hydraulic press are there? (2)
- Free standing hydraulic press
- Portable hydraulic press
As with all fits, the contacting surfaces must be free from:
Grit
it is most important that the axis of the internal and external parts stay in line with each other during a forced fitting. If either part is canted, one or both parts:
May be damaged
tests have shown that smooth mating surfaces free from lubricant give the best grip, however:
anti seize applied before assembly helps reduce seizure and abrasion
to shrink fit parts, the outer part is heated, causing it to expand. What could you use as a heat source? (6)
- Hot water, oil baths
- steam
- oxy/gas hand torches
- oil/gas/electric furnaces
- electronic resistance heating
- electronic induction heating
Allowances for a shrink fit are usually determined by consulting:
the working drawing or suitable tables
The required temperature change depends upon the total expansion required and on the:
coefficient of linear expansion of the metal
instead of heating a hub, the shaft may be:
contracted by cooling
when expansion fitting (freeze fitting), what methods can be used to cool the shaft? (4)
- Industrial refrigerator
- liquid air
- alcohol and dry ice
- liquid nitrogen
This method of cooling gives easy control of temperature and can reach temperatures of around -50C (-58F)
Industrial refrigerator
This method of cooling is able to reach temperatures as low as -120C (-184F)
Liquid air
This method of cooling is similar to liquid air, but a lot safer due to the absence of oxygen
Liquid Nitrogen
This method of cooling is done without expensive equipment. It can produce temperatures of -50C to -60C (-58F to -76F).
Alcohol and dry ice
Note: This method causes frost formation on parts, which could be a problem
Hydraulic presses are classified by: (3)
- Type
- Force output
- function
Hydraulic presses are rated according to their:
Pushing capacity in tons
Mechanical arbor presses are used for ____ jobs
light
an advantage of an arbor press is that it gives the user:
a sense of the amount of pressure being applied
A free standing hydraulic press consists of a frame of substantial construction with devices for holding work pieces, a ram for pushing, and is actuated by:
a pump
