Course: Injection molding defects – Sink Marks

135.60 $ incl. tax


There are many parts that will be visible while in use.

Due to the contraction of the melt during its solidification very often sink marks appear on the part surface.

Very often sink marks are not accepted by customers. Therefore it is important to find solutions in order to avoid this kind of problem.

SKU: EL12101 Category:

You will learn

  • About the causes of sink marks.
  • The reason of back flow.
  • Which parameter need to be balanced.

This enables you to

  • Identify the main cause of sink marks in your process.
  • Avoid back flow.
  • Choose the right parameter to counteract sink marks.


About the course: Injection molding defects - Sink marks

One of the most present surface defects on plastic parts are sink marks.

No matter if the cause of sink marks is based in the design itself or in the process, the appearance of the part does not look good.
So it is up to the setter to find the best way to reduce and in the best case avoid sink marks.

The current course describes the basics as well as solutions in order to avoid sink marks.
In three lessons all important information is given to ensure the best production of a part if it comes to sink marks.


This course is for

Everyone who is curious about the topic.
This includes especially people working as:

  • CAE-team
  • Setter
  • Injection molder
  • Quality manager
  • Department leader
  • Simulation-Team
  • Head of Design


Course details

For basic skill level

Around 40 min in duration

Video On-Demand lessons (1)

Spoken script

Expertise knowledge described step-by-step in text

Additional explanations on important technical terms

Full access on computer or mobile for one year

Certificate of completion when you finish the course

(1) Video streaming is part of the e-learning and shall be accessible in your browser.

Course Specialist

Prof. Dipl.-Ing. Peter Wippenbeck



For many years, Prof. Dipl.-Ing. Peter Wippenbeck has been connected to injection molding technology. He started with mechanical engineering and application technology. Even then, the aim was to achieve a perfect product with the best possible economic efficiency. Quite a few customers confronted him with problem cases and asked for solutions and optimized settings in production.


He took on teaching duties at Aalen University, in Germany, in the field of plastic technology in the 70’s to examine the experiences from industry and to pass on his knowledge to future generations of engineers. Soon, he got a managing position there. His work, with international cooperation, led to the establishment of the master’s degree program in Polymer Technology.


Initiated by the professional association of GKV (called TecPart), industrial training in the field of injection molding was intensified additionally to the engineering degree: Several thousand participants at seminars have already been trained by him and qualified in Aalen including a considerable number of foreign employees and trainers, especially from Thailand, India and Indonesia.


In organizational terms, these activities are located at the Steinbeis Innovationszentrum Kunststofftechnik (SIZK, a non-profit company of Steinbeis Innovation gGmbH), while problem-solving is the responsibility of the Steinbeis Transfer Zentrum Aalen Kunststofftechnik (STAK). In both institutes, the author has been engaged in knowledge transfer in the sense of quality improvement and efficiency in injection molding technology.