Question

The following data resulted from a study taken on a horizontal milling machine:

Pieces produced per cycle: 8.

Average measured cycle time: 8.36 minutes.

Average measured effort time per cycle: 4.62 minutes.

Average rapid traverse time: 0.08 minutes.

Average cutting time power feed: 3.66 minutes.

Performance rating: 115 percent.

Allowance (machine time): 10 percent.

Allowance (manual time): 15 percent.

The operator works on the job a full eight-hour day and produces 380 pieces. How many standard hours does the operator earn? What is her efficiency for the eight-hour day?

Answer 1

Step 1: Find the Normal TIme For the Machine and Worker:

Normal Time = (Observed Time X Performance Rating) /100

Thus,

Normal Time for Worker = (4.62 X 115) / 100

= 531.3 / 100

= 5.313 Minutes

Normal Time for the Machine = Observed Time (∵ the performance rating is 100% for the machine) = observed cycle time - observed worker time = 8.36 - 4.62 = 3.74 Minutes

Step 2: Find the total Standard Time for the Machine and Worker

Standard Time = Normal TIme X ( 1 + Allowance Factor)

Standard Time For Worker = 5.313 X (1 + 0.1) = 5.844 minutes

Standard Time for Machine = 3.74 X ( 1 + 0.15) = 4.301 minutes

Hence, Total Standard Time = Standard time for worker + standard time for machine = 5.844 + 4.301 = 10.145 Minutes

Step 3: Standard Piece Time = Total Standard Time / Pieces per cycle = 10.145 / 8 = 1.2681 minutes (Rounded to 4 decimals)

Step 4: Standard hours (SAH) earned = (Standard Piece Time X Pieces produced / 60)

= ( 1.2681 X 380) / 60

= 8.0313 (Rounded to 4 decimals)

Step 5: Operator efficiency (On-standard) in percentage = (Total SAH Earned / Total hours worked) X 100
= (8.0313 / 8) X 100

= 1.0039 or 100.39 % (Rounded to 2 decimals)