Surface Defects: A Guide to Correcting the Problems

The surface finish requirements defined by customers can vary from a rough finish with allowable discontinuities to a defect-free mirror-like finish. Hence, the surface finish issues discussed in this publication are primarily those that affect appearance, such as metal flow related defects. The die casting process can provide an exceptional surface finish but typically requires special attention to the process details. This book describes the process details that impact surface finish and is intended to provide help and information for the practitioner in developing and maintaining defect free surfaces that meet customer expectations.

TABLE OF CONTENTS

Introduction…………………………………………………………….1

Some Basics About Metal Flow……………………………….2

Atomized Flow………………………………………………………..7

Improving Surface Finish & Correcting Cold Flow Problems……………………………………………………………….11

Fill Time……… ……………………………………………………….11

Correcting Problems with Fill Time………………………..13

Die Temperature……………………………………………………14

Adjustments for Die Temperature…………………………15

Guidelines for Proper Water & Hot Oil Connections…18

Metal Flow Pattern – Gating………………………………..20

Other Factors to Consider ……………………………………26

Summary………………………………………………………………27