Thread Consumption Equation

Thread consumption may be carried out by an equation that is derived from stitch geometry for various stitch types. The equation is flexible and applicable to any given length of the seam, they are shown for one inch only, and may be multiplied by the length of the seam to determine the total thread consumed. 

The following variables are considered to develop mathematical equations.

C	=	Consumption per inch
W	=	Width of seam
T	=	Thickness of materials
S	=	Stitch per inch
N	=	Stitch length in inch
N X S	=	1 (as 1 ÷ S = N)
(*)	=	2W+N assumes for cover thread

Stitch Types	Stitch Name	Equation
101	Single-thread Chain Stitch	C = 3 + 2TS
301	Lock Stitch	C = 2 + 2TS
401	Two-thread Chain Stitch	C = 4 + 2TS
406	Cover-seaming Stitch	C = 7 + 2S(T+W)
407	Cover-seaming Stitch for Attaching Elastic	C = 9 + 2S(3T+W)
504	3-Thread Overlock	C = 4S(W+T) + 3
514	4 Thread Mock Safety	C = 5 + 2S(3T+2W)
516	5 Thread Safety Stitch	C = 2S(2W+3T) + 9
*602	Cover Stitch	C = 8 + S(5W+4T)
*605	Cover Stitch	C = 10 + 2S(2W+3T)
*607	Flat Seaming Stitch	C = 12 + 4S(W+2T)

The above equations are developed for commonly used stitch types.

Derivation of equation summary

Stitch class - 101

C = (3N + 2T)S

    = 3NS + 2TS

    = 3 + 2TS         (N X S = 1)

Example,

Stitch class - 101

SPI (S) = 10

Stitch Length (N) = 0.10

Seam Thickness (T) = 0.05 

C = 3 + 2TS

   = 3 + 2*0.05*10

   = 4

Stitch class - 301

C = (2N + 2T)S

    = 2NS + 2TS

    = 2 + 2TS         (N X S = 1)

Example,

Stitch class - 101

SPI (S) = 10

Stitch Length (N) = 0.10

Seam Thickness (T) = 0.05 

C = 2 + 2TS

   = 2 + 2*0.05*10

   = 3

Stitch class - 401

C = (4N + 2T)S

    = 4NS + 2TS

    = 4 + 2TS         (N X S = 1)

Example,

Stitch class - 401

SPI (S) = 10

Stitch Length (N) = 0.10

Seam Thickness (T) = 0.05 

C = 4 + 2TS

   = 4 + 2*0.05*10

   = 5

To understand the fact clearly, you have to draw the stitch geometry.

Ref.

http://www.unionspecial.com/