Troubleshooting Surface Defects in Injection Moulding

Dates: To be verified.

Duration: 3 days in total ( 2 x half day online morning sessions plus 1 full day online practical session)

Location: Online

Accreditation: Certificate of Attendance

Full Fee: €450

Course code: TSD

Programme overview

This course will examine surface defects in injection moulded parts from root cause through to practical sessions to eliminate these defects. Course delivery will be over two half-day sessions looking at surface defects in detail followed by one separate practical session live-streamed from our Arburg and Fanuc electric moulding machines.

Topics covered include:

  • Cavity balance
  • Cavity measurements – sensors, etc
  • Cooling issues
  • Black specks
  • Blush
  • Brown streaks
  • Bubbles
  • Buildup
  • Burns
  • Cloudiness
  • Colour swirls
  • Contamination
  • Cracking
  • Delamination
  • Dimensional issues
  • Excessive/erratic cycle time
  • High fill pressure
  • Flaking
  • Flash
  • Flow lines
  • Glass fibres on surface
  • Glossy/shiny spots
  • Jetting
  • Parts sticking
  • Ejector Pin push-through
  • Read-through
  • Scuffs and scratches
  • Short shots
  • Sinks
  • Splay
  • Sticking sprues
  • Strings
  • Voids
  • Warp
  • Weld lines

Learning outcomes


  • Understand the root cause of various surface defects
  • Be able to troubleshoot surface defects using different machine settings
  • Understand the effect that mould design and part design has on surface defects
  • Understand the effect that temperature control has on surface defects
  • Understand the effect that material drying has on surface defects.

Who is the course for:


This course will suit anyone who wants to better understand surface defects in injection moulding. Typically this includes Process Technicians, Process Engineers, Supervisors, Quality Technicians, Quality Engineers, Validation Engineers, Toolmakers, Part Designers.

There are no pre-requisite courses/ modules required before attending this course, however this course would be an excellent refresher for those having attended previous injection moulding training.

Course Content


Day 1: This is a half day theory session. We will look at the methodology used to identify the type of defect, and the approach taken to fix the problem.

We will use an A-Z format, using images to support, to identify surface defects, and give suggestions to fix the problems under 3 different headings – 1) the Injection Mould: 2) the material and 3) the moulding process


Day 2: A half day theory session. A continuation of day one, completing A-Z of surface defects, adding in real-life examples of experiences, and lead-in to day 3.


Day 3: This will be a full day virtual practical session, live streamed from our Arburg 60t electric moulding machine. The morning will look at defects such as ejector pin marks, parts sticking, stringing, weld lines, flow lines, record grooves, blush marks, voids. We will also look at optimising the process to avoid multiple defects on the same parts by using injection speed profiles and holding pressure profiles. There will be a focus on using machine data to drive decision making – including injection and holding pressure/ speed/ stroke curves, injection time,

The afternoon session will be a practical session, live streamed from our Fanuc 100t electric moulding machine. We will look at defects such as burn marks, flow marks, degradation, black specks, sink marks, short shots, flash, delamination, splay, warpage. Each of these defects will be created during the practical session and we will show different options being used to fix these defects. This session will also show how to use process control/ trend charts to visually monitor the process once optimised to check for consistency.

Trainer Profile


Steve O’Leary 

Steve graduated from Athlone IT having studied Plastics Engineering from 1988 to 1992. He has delivered training in Injection Moulding for First Polymer Training since 2000, initially joining FPT Skillnet as the Training Centre Manager.


Martin McGirl

Martin McGirl has over 30 years experience in the Toolmaking and Plastics Industry. Initially he served his time as an Injection Mould Toolmaker, before progressing to Tool and Product Designer and then to Technical Sales and Business Development Manager.

Expertise: Experienced Toolmaker – mould manufacture and assembly, and mould repairs and service. DFM on component-part design, mould tool design and mould trouble shooting of high-cavitation, high complexity, multi-cavity Pharma/ Medical Device moulds.

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