What is Pitch Time, Pitch Diagram and how to make a Pitch Diagram?

Pitch time: In industrial Engineering, Pitch time is a ratio of total SAM of garment and number of operations to be set for the style. Or

Pitch Time = Garment SAM/No. of operations.

Pitch time is used for line setting and calculating production target for the line.

Pitch diagram:

A graphical presentation of individual operation’s time (SAM) and pitch time on a same chart is called pitch diagram. For example see the following chart (Fig.1). At this chart on X-axis operations name and on Y-axis time value is depicted. The blue line is showing individual operation SAM and red line is showing pitch time.

Fig.1: Pitch Diagram (SAM Vs Pitch Time)


Usage of Pitch Diagram:

Pitch time is to calculating machine requirement in each operation.
Pitch diagram is used for line balancing in an assembly line. Pitch diagram is made on operator’s production capacity per hour and target quantity per hour in pieces for easy understanding.


How to make a Pitch Diagram

To make a pitch diagram on operator’s capacity Vs line target collect information as following. First conduct a capacity study for all operators and find out how many pieces operators are making at each operation. Where more than one operator is doing same operation, sum up their capacity for that particular operation. With the capacity study data make one table on spreadsheet as following table-1. 

For example, the line is making ladies blouse. Operations are listed in column B as per operation sequence (all operations are not taken). In column C number of pieces is listed according to the operations that can be produced by the operators. Add one more column ‘D’ and write target quantity (in the example -27) against each operation.

Suppose that hourly production target is 27 pieces for the line. So to meet the target at the end of the line you should get minimum 27 pieces per hour from each operation and for the preparatory operations capacity should be more than 27 pieces. Now draw a line chart with capacity and line target (Fig. 2). This chart is also called as “Pitch Diagram”. The blue line is showing actual capacity at each operation and Red line is presenting the target quantity.

In the chart, the blue line moves up and down. Where blue line is below the target line, you will get pieces which are less than target quantity. These operations are the potential bottleneck for the line. On the other way, where blue is top of the target line, it means operators have potential to produce more pieces on those operations if they are provided work. From the Pitch diagram, it is easy to understand which operations are bottleneck and where operator’s full capacity is not being utilized.

Table-1: Data shown in the following table and chart are assumed only for example. Follow above steps and make your own “Pitch diagram” with real data of a line. 
A
B
C
D
Sl. No.
Operations
Capacity/Hour
(Pieces)
Target/hr
(Pieces)
1
Collar run stitch
35
27
2
Back dart making
27
27
3
Sleeve slit binder
29
27
4
Front placket attach
21
27
5
Front placket finish
20
27
6
Front dart making
33
27
7
Shoulder Join O/L
30
27
8
Shoulder edge stitch
40
27
9
Sleeve attach O/L
50
27
10
Side attach
20
27
11
Cuff attach
17
27
12
Cuff  finish & Tacking
16
27
13
Collar  attach
24
27
14
Collar finish
24
27
15
Bottom Hem
27
27
     
Fig. 2: Pitch Diagram (Actual capacity Vs Target quantity)



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