An operator must load and unload a machine that washes lubrication and metallic

ID: 399936 • Letter: A

Question

An operator must load and unload a machine that washes lubrication and metallic debris off newly lathed metal parts. The operator loads a tray with two-dozen (24) lathed parts. Taking a tray of 24 freshly washed parts out of the machine and loading a second tray of 24 unwashed parts has a normal time of 28 seconds on average. The machine wash cycle is 1 minute and 20 seconds. Every eighth cycle, the operator must empty both trays and spray them down to remove debris that may have collected in the mesh. This washing process takes 48 seconds (normal time) on average. The manual parts of the task that involve the operator (loading & unloading, washing) have a PFD allowance of 20%. Machine PDF allowance is 2% (machine is generally very reliable, though on rare occasions wash hoses become clogged and must be unclogged).

Calculate the normal cycle time for this process including the irregular elements expressed in minutes. (

b) Calculate the standard time for the operation

c) Assuming an 8-hour workday, was is the corresponding standard daily production quantity for the machined parts expressed in pieces per shift?

Explanation / Answer

Manual

Machine

unloading

Loading-

washing

Remove debris(every 8th cycle)

Observed time

1 minute 20 seconds

48 seconds

Rating

Normal time

28 secs

Observed time is time taken for the activity as observed

Norma time is time taken when the activity takes place at faster or slower rate

Normal time = observed time *rating

Normal time of operation

= Normal time of activities + normal time of activity that takes place every nth cycle

= Normal time (manual-loading and unloading) + Normal time (machine) + normal time of activity that takes place every nth cycle

=28 secs + machine observed time * rating + Observed time of activity that takes place every nth cycle *(rating /number of cycles)

= 28 secs + 100 secs * 1 + 48 secs *(1/8)

=28 secs + 100 secs * + 6 secs

=134 seconds

Standard time is normal time plus allowances for rest, delays etc(PFD- Personal time, fatigue, delays)

Machine Allowance pfd =2%

Manual labour (loading & unloading, washing) Allowance pfd =20%

Standard time of operation

= Normal time + allowances

= Normal time + Machine Allowance + Manual labor Allowance

=134seconds + 2% of 100 secs + 20% of (28 secs+6 secs)

=134+ 0.02 *100+0.2*34

=134+2+6.8

=142.8 secs

Note

Corresponding standard daily production quantity

= working hours /standard time

= 8hrs/ 141.6 secs

= [ 8*60*60] / 142.8

=201.68 pieces

Or 201 pieces for an 8 hour shift