TPU Surfboard Fin Injection Molding Parts

Recently, Yeeshine made custom mould for one OEM design TPU fin, it is made by TPU clear or ABS or Nylon material. Fins are important because they are the device that gives you stability, control and direction on your surfboard. They help you maintain your speed and “cut” through the water, in a way that would be impossible on a finless board.

Here we would like to share with you the injection mold making process from design, prototype to injection molding parts.

Basic part information for TPU injection molding:

● Part size: 213*145*8.6mm

● Plastic material: TPU

● Finish: Glossy Finish（SPI A-2）

● Color: Translucent black

● Production volume: 10K

According to the sketch drawing and carbon fiber fin prototype, our designer make a new 3D model to meet the final fin dimension.

Basic mold information:

● Gate type: Edge gate

● Cavity number:1*1

● Steel Material: S136H

● Shrinkage:1.11

● Mold Dimension: 400*350*310 mm

● Mold Weight: 220kg

TPU injection molding making process

Before making the injection mold, Yeeshine made two prototypes through silicon vacuum casting based on customer’s final 3D drawing. In this way, we are aware of the assembly test result and size fitting. Below are two material for test, ABS and TPU material.

YEESHINE will make DFM analysis of the plastic part and verify some important information with the customer, like parting line, gate position, ejection, etc. After the verification with the customer, YEESHINE made 2D & 3D design layout of the injection mold.

The actual injection mold completed as following picture shows:

Injection mold making took 4 weeks, YEESHINE did T1 sample testing on the scheduled time. Below is the T1 trial parts:

To meet the requirement of “ the fin should be full with no shrinkage, the edge burr should be none with smooth.”, we had discussed internally and talked to customer to find solutions and balance at quality level. Showing different translucent black level for choice as below:

TPU material moulding effect is not stable, it appears different kinds of defect if machine de-bug have little bit difference. When shrinkage solved, it cause some melting line; when melting line not visible, the edge burr comes out.

Before mass production, we also faced the melting line issue at the fin base debossed area when molding, but fortunately we come out the solution and keep melting line as less/weak as it is. Production is going smoothly with satisfied quality after team’s efforts on mold improvement and moulding technique.  

Remark by YEESHINE

Injection mold making is a customized process, YEESHINE engineers work closely with customer to understand their requirements and make proper solution to achieve the best possibility,we are not simply a mold manufacture to deliver the parts according to design, we offer solutions and deliver satisfaction.