Comparison about methods of double layer shoe sole injection

9th, May, 2016

Generally there are two methods of double layer shoe sole injection with upper by PVC DIP machine, as following:

Method one: by double-color injection moulding machine(double injection)

step 1: shape bottom layer sole with dummy plate

step 2: shape second layer sole with aluminum last

Method two: by single color injection moulding machine (single injection)

step 1: put the completed sole into the mould

step 2: shape the second layer sole with aluminum last

And we compared two methods from four sides:

Machine and mould specification

double injection

single injection

machine specification

two injection units

single injection unit

mould specification

double color shoe mould (with dummy plate)

single color shoe mould (without dummy plate)

The single injection method need less investment in machine and shoe moulds.

Shaping time

The single injection method will take less time for sole shaping than double injection method, which means, the single injection method results to more productivity in same time.

Defective rate

Assume that the defective rate of each injection is 3%. The single injection method will get the defective rate as 3%, and the double injection method will get (1-0.97*0.97) as 5.9%. So the single injection method has lower defective rate than double injection method.

Human work

The single injection method need extra one to put the completed sole. But in some factories, this one is also arranged by flexible shift.

Here is the conclusion after comparison.