3) L3 Principles of Mechanical Manufacturing Engineering

Why is it so important to carry out alignment tests on machine tools? Choose three.

• Squareness to neck or legs.

• Straightness of legs.

• Straightness of beds.

• Squareness to tables or columns.

• Level of beds.

What three problems that could occur if machine tools are not correctly aligned?

• Increase friction.

• Increase in energy consumption.

• Increase talking period.

• Increase in noise.

• Increase floor space

What three features explain the recirculating ball lead best?

• In a recirculating ball leadscrew both the leadscrew and the nut have a precision ground form in which precision ball bearings, are allowed to run.

• The ground thread form can not be either semi-circular or 'gothic arc'. Enough balls are inserted to completely support the screw/nut assembly.

• The form is so designed that contact only takes place on opposite faces of the assembly.

• The ground thread form can be either semi-circular or 'gothic arc'. Enough balls are inserted to completely support the screw/nut assembly.

• The form is not designed that contact only takes place on opposite faces of the assembly.

‘Slip-stick’ is a condition that affects machine tools, what does this mean?

• Slip-stick is a condition that occurs when large movements between four lubricated elements are required. The mating elements stick to each other and resist motion, and a jerky action is produced.

• Slip-stick is a condition that occurs when small movements between two lubricated elements are required. The mating elements stick to each other and resist motion, and a jerky action is produced.

• Slip-stick is a condition that does not occur when small movements between two lubricated elements are required. The mating elements stick to each other and resist motion, and a cake action is produced.

• Slip-stick is a condition that occurs when small parts between two non-lubricated elements are required. The mating elements stick to each other and resist motion, and a jerky action is produced.

What arrangements, describe how rotational movement is achieved. Two parallel shafts, 600 mm apart, rotating at different speeds, without any slip.

• Tooth band connected to two shafts. Tooth pulleys are not positioned and aligned on each shaft. Diameter of the pulleys will depend on the input and output speeds.

• Tooth belt connected to two shafts. Tooth pulleys are positioned and aligned on each shaft. Measurements of the bands will depend on the input and output speeds.

• Tooth belt connected to two shafts. Tooth pulleys are positioned and aligned on each shaft. Diameter of the pulleys will depend on the input and output speeds.

• Tooth belt connected to one shaft. Tooth pulleys are positioned and aligned on each shaft. Diameter of the pulleys will depend on the input and output speeds.

Which part of the cam is the LIFT and which is the DWELL?

(Remember this sketch)

• Top = DWELL

  Bottom = LIFT

• Top = Lift

  Bottom = DWELL

• Top = DWELL

  Bottom = DWELL

• Top = LIFT

  Bottom = LIFT

How does a carriage on a centre lathe move back and forth (traversed) a long the bed?

• The pinion is fitted with a hand wheel, this is located on the apron in such a position that the teeth are engaged with the teeth of a rack secured to the under side of the machine bed. The motion of turning the hand wheel does not allow the carriage to traverse along the bed.

• The part is fitted with a hand wheel, this is located on the saddle in such a position that the teeth are engaged with the teeth of a rack secured to the under side of the machine bed. The motion of turning the hand wheel allows the carriage to traverse along the bed.

• The pinion is fitted with a hand lever, this is located on the apron in such a position that the bands are engaged with the teeth of a rack secured to the under side of the machine bed. The motion of turning the hand wheel allows the carriage to traverse along the bed.

• The pinion is fitted with a hand wheel, this is located on the apron in such a position that the teeth are engaged with the teeth of a rack secured to the under side of the machine bed. The motion of turning the hand wheel allows the carriage to traverse along the bed.

What four methods can be used to change spindle speeds?

• Electrical/electronic, infinitely variable, cone pulleys, and stop gears.

• Electrical/electronic, infinitely variable, cone pulleys, and sliding gears.

• Electrical/electronic, infinitely variable, one pulley, and sliding gears.

• Electrical/electronic, infinitely variable, cone pulleys, and sliding parts.

What part of the spindle speed mechanism is this called?

(Remember this picture)

• Cone pulley

• Metal pulley

• Rubber pulley

• Ice pulley

How is the sliding gear (Norton gearbox) used to control the feed speed on a centre lathe?

• The drive is not through a gear train from the back stock spindle. The box consists several different size gears and a sliding gear selector.

• The drive is through a gear train from the headstock spindle. The box consists several different size gears and a sliding gear selector.

• The drive is through a gear train from the headstock spindle. The part consists one different size gears and a sliding gear selector.

• The drive is through a band train from the headstock spindle. The box consists several different size metal parts and a sliding gear selector.