Machine Production Records - Case Study Example

The rated production rates for machine types 1, 2, and 3 were 700, 200, and 155 parts per minute, respectively, but actual production rates varied. Helen felt that factors such as quality of input material, worn or "changed-out" dies, and dirty or poorly maintained presses would probably affect production.

The facility had always kept daily production records, but from what Helen could tell, no one ever consulted them or did anything with them other than to put them in file cabinets at the end of each reporting period.

The machines were scheduled for a shift of 7.75 hours each day. The operators recorded the hours of operation manually on clipboards kept near each machine. The actual quantities of parts produced were determined from automatic counters on the machines. The data on the next two pages (and in file PROD) were derived from these logs.

Can you advise Helen?

 This case is based on a real production line situation, though the name of the organization and the exact nature of the product have been disguised. The data were provided by Ted Manzanares.

Solution

There are three variables that present the problem: The no. of parts produced the no. of hours that they spent and the number of hours when the press was down.

We compute the deliverable statistics.

M type

Frequency

Percentage

700

28

24.1

200

35

30.2

155

53

45.7

 

116

100.0

Statistics for the variables.

Variable

Statistics

Value

No. of parts produced

Mean

97610.26

 

Median

58707.50

 

Variance

9600782707.9

 

Standard deviation

97983.584

 

Standard error

9097.547

 

Minimum

5084

 

Maximum

320242

 

Interquartile range

57286

Hours of production

Mean

5.7784

 

Median

6.8300

 

Variance

4.886

 

Standard deviation

2.21045

 

Standard error

0.20524

 

Minimum

0.58

 

Maximum

7.75

 

Interquartile range

4.06

Hours press was down

Mean

1.4859

 

Median

0.5400

 

Variance

3.422

 

Standard deviation

1.84984

 

Standard error

0.17175

 

Minimum

0.00

 

Maximum

7.17

 

Interquartile range

2.67

 

Statistics for each type

Variables

M type

No.

Mean

Standard deviation

Standard error

 

1

28

259627.54

58444.892

11045.046

 

2

35

43210.43

17238.352

2913.813

 

3

53

47940.64

24976.660

3430.808

Total

 

116

97610.26

97983.584

9097.547

Hours of production

1

28

6.7668

1.38309

0.26138

 

2

35

5.8906

2.16969

0.36674

 

3

53

5.1821

2.41612

0.33188

Total

 

116

5.7784

2.21045

0.20524

Hours that press was down

1

28

0.9593

1.35500

0.25607

 

2

35

1.8594

2.16969

0.36674

 

3

53

1.5175

1.81441

0.24923

Total

 

116

1.4859

1.84984

0.17175

 

Highest and lowest values in each variable

Value

 

No. of parts produced

Highest = 320242

316080

 

315124

 

312501

 

311877

 

Lowest

5084

6899

 

8142

 

8675

 

8954

 

Hours of production time

Highest 7.75

7.75

 

7.75

 

7.75

 

Lowest

0.58

0.58

 

1.08

 

1.08

 

1.08

 

Hours that the press was down

Highest 7.17

6.25

 

6.00

 

5.83

 

5.58

 

Lowest

0.00

0.00

 

0.00

 

0.00

 

0.00

 

 

Based on the statistics above, we can advise Jane for a machine type to be considered as being effective, it must be able to produce parts that are between 5084 and 320242 in number. The machine type must also be able to operate a minimum of 0.58 hours and a maximum of 7.75 hrs. From the statistics of central tendency, machine type 2 is the best for producing parts and also uses minimum time. When the press was down, machine type 2 is the best since it has the minimum standard error.

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