IE in Apparel Manufacturing-7: Machinery and Manpower Planning

Machinery and manpower planning is one of the major activities which consumes a significant amount of time and effort of an IE at a garment manufacturing unit. Companies struggle to arrange and allocate desired machines and manpower to get the intended output, and many a times, unavailability of machine and manpower is taken as an excuse to hide or cover up the failures. No doubt, these resources are vital for success but the bigger question is ’Whether the available resources are utilized at the fullest?‘

Though, allocating the right person to the right task with right machinery is one very sensitive issue, it is not given due importance by most of the IEs. A mismatch of requirements (may be manpower or machinery) to the actual allocation may lead to serious imbalances in the process, this may hamper the performance of the setup. Manoj Tiwari, Associate Professor, NIFT Jodhpur and Dr. Prabir Jana, NIFT Delhi discuss the significance of machine and manpower planning and suggest a logical approach considering a number of constraints in practical work environment.

An effective and efficient machinery and manpower planning machinery is critical for the success of any process and requires a good understanding of IE concepts, good soft skills (interpersonal skills) and of course a habit of playing with numbers. It is the culmination of understanding all other IE processes discussed in the previous articles of this series.

Different Planning Techniques

In order to meet the delivery deadlines (say 2,500 units per shift of 8 hours), one needs to allocate machinery and manpower for each process and this is called target based planning. Sometimes, it is the other way round and the targets are set based on the availability of resources (machine and manpower) and this kind of arrangement is called resource based planning. For machinery and manpower allocation it is important to know the SAM values of each operation, which can be defined as work content of an operation when performed by standard operator that includes the P&F&D allowances. For example, if SAM value of belt loop making operation is 0.5 min., then target for one ‘standard’ operator (means an operator with 100% rating in that operation) should be 960 pieces (480 minutes/0.5 = 960) per 8 hour shift.

Let’s understand this with an example wherein one stitching line needs to be set up. Assuming that the Daily Production Target is 1,500 units/line/shift (480 min./shift), total SAM of the style is 3.96 and SAM values for different operations (hypothetical) are given below:

Production figures (hourly and shift) for each operation may be calculated easily using simple mathematics. For example, coin pocket attach takes 0.25 minutes per pocket, so 240 coin pockets are produced per hour (60/0.25 = 240) and it would be 1‚920 coin pockets/shift of 8.0 hrs.) may be attached. By doing so we may be getting different production values (mathematical output) for different operations depending on the time consumed in performing that particular operation. Based on the production that can be achieved per shift and required target (1,500 units/shift), number of machine required for each operation may be calculated as shown in Table 2. For coin pocket attach we need 0.78 machine (target 1,500 divided by production 1,920). This kind of allocation is target-based allocation.

Machine & Manpower planning

Suppose in above example the average rating of the operators is 85%, average absenteeism is 10% and average worker utilization is 80%. In 480 minutes (8 hours) available, an average production of 121 units (480 min./3.96 min.) is thus possible and the total number of operators required will be 12.40 (1,500 units/121 units). This is true when everything is ideal, no absenteeism, 100% average operator rating and 100% manpower utilization. But considering these constraints in real scenario (say 15% absenteeism, 90% average operator rating and 80% utilization), the actual manpower would be 20 operators (12.40/(0.85 X 0.90 X 0.80 = 20.22 operators), out of this 10% (i.e. 10% of 20.22 = 2) will be kept as buffer manpower to counter absenteeism and will not be allocated any designated operation. As the manpower is revised upwards‚ keeping the constraints in mind, the target also to be revised to 151 (121 divided by 80% utilization).

As there are 9 operations in the style, ideally we require 22 operators and the pitch time is calculated as 0.18 min. (3.96 divided by 22). But in reality we have 18 (20-2 = 18) operators available in above style to meet the target. As the SAM is 3.96, the pitch time will actually be 0.22 (3.96 divided by 18). Accordingly, the theoretical manpower/machine allocation can be as shown in Table 3. If we get all 18 people present (Column 4), all works at equal rating of 85%, and line utilization is 80%, each operation will produce around 185 pieces per hour [(60 divided by SAM) X No. of machines 0.85 X 0.80] and we will have a perfectly balanced line.

But in reality we cannot have machines or operators in decimal numbers and secondly every operator will have different rating (although the average of factory is 85%) in different operations and thus production will vary for different operations. So we first add up the similar machines and then round it off. Total SNCS machine requirement will be (2.27+1.36+0.73 = 4.36) ~ 5 machines, total SNLS machine requirement will be (3.41+1.14+4.09+1.36 = 10.0) ~ 10 and so on. Although total actual machine is now 19 (5+10+3+1), but even then operation number 2, 5, 7, & 9 are having less machines than required (Column 5). This kind of machine imbalances will always remain in a line however much we minimize. Even if all operators work at equal 85% rating we can see how hourly production will vary from operation to operation (Column 6).

Operator rating is the operator’s abilities to perform the task with varying skills. An operator (A), who is capable of performing work on 3 different kinds of machines say SNCS, SNLS and FOA, possess highest skill level (100% rating) in SNCS belt loop making and lowest of 65% rating in FOA. A sample format of skill matrix is shown in Table 4.

To achieve target of 151 pieces per hour for Operation 1, we need one operator of 125% rating. From the skill matrix we can see that operator ‘A’ has 100% rating and ‘E’ has 50% rating in Operation 1, so we allocate ‘A’ fully and ‘E’ partially half of the time in operation 1. Operator ‘A’ will produce 120 pieces per hour and operator ‘E’ will produce 30 pieces per hour. Together, both ‘A’ and ‘E’ Operators will produce 150 pieces per hour. While operator ‘A’will be completely occupied, operator ‘E’ will be available half of the shift time for working on other operation. Similarly, to achieve target of 151 pieces per hour for Operation 2, we need one operator of 75% rating. From skill matrix table we see operator ‘A’ and ‘C’ are capable of doing Operation 2, however as operation ‘A’ is already allocated in Operation 1, we have no other choice than to allocate operator ‘C’ in 2nd operation. Please note that output per hour for operation 2 will be slightly lower than target (140 pieces) (as 70% rated operator was allocated against requirement of 75%). This is how we need to allocate best possible Operator to each operation to meet the target. Once initial allocation is done for all operations, a line can start functioning, however there will be imbalances due to above mentioned variability and line need to be continuously balanced which is the domain of line managers and IE does not intervene.

Conclusion

The apparel production environments consist of a number of factors affecting the output. High level of human intervention makes it more complex and uncertain. In such scenario‚ it is very important to allocate the resources in best possible manner and ensure maximum utilization. Still it’s worth mentioning that there is no wrong line planning‚ but there are always a better plan. In manpower planning we should remember that we are playing with numbers which are average figures generated by human beings and thus subject to variation.