What is Needle Downtime? Calculation of Needle Downtime in Garment Sewing?

Needle Downtime

For both sewing floors and sewing factories, downtime is a key performance indicator (KPI). The term 'needle downtime (NDT)' is frequently used in the clothing industry to represent the total amount of time or a percentage of the total amount of time that a sewing machine is running while sewing a garment together. Many people think needle downtime is lost time, but it is the opposite in meaning.

Calculation of Needle Downtime

To calculate the needle downtime, following the time study procedure is best. From the practical experience, the needle downtime calculation procedure is given below.

 

✔ Select a specific workstation and an operator
✔ Record the operator details. Like the name, rating and most importantly, how many processes she did.
✔ Do as usual time study and mainly record stitching (time of needle running) time separately.
✔ Find time for machine running element (stitching) from the time study sheet
✔ Study 20-25 cycle time for same operation.
✔ Determine the average needle running time and the total number of production.

Let say,

Process average machine running time (needle downtime) = 15 seconds

Total poece produce = 450 pcs

Therefore,

Needle Downtime =  450 × 15 = 112.5 Minute = 1.875 Hour

Usually needle downtime expresses as percentage.

Let say, Shift hour was 8 hours = 480 min.

So, Needle Downtime = (112.5/480) × 100% = 23.44%