Seven deadly wastes, pt.1: scrap

14 Apr 2023

No one likes to talk about cost losses in the production process, and even less like to track the steps in the chain that might cause them. However, even Industry 4.0 isn’t immune to human factor, and accidental waste can just happen, and you have to deal with that.

   seven wastes in lean manufacturing diagram

According to Toyota Production System, which has given birth to many Lean manufacturing principles, there are seven possible causes for waste during the production process:

  • Defects (scrap)
  • Overproduction
  • Unnecessary motion
  • Unnecessary inventory
  • Waiting
  • Transporting
  • Inappropriate process organization

Often dubbed as “seven deadly wastes”, these cause can seriously hinder your production capacities and create huge cost losses at the facility. The good thing is, you can deal with them, and the process of waste elimination is easier than you think.

In this article cycle, we’ll try to address each of the “seven deadly wastes” and help you build a strategy on how to deal with them using modern solutions and increase your production efficiency. So, let’s begin with the first one on our list: scrap.

What is scrap?

Scrap is a material or part obtained during the manufacturing process, which is unusable in further production steps because it doesn’t meet the needed requirements. High scrap rates can significantly impact a company’s profit, so addressing the cause of scrap at your facility should be one of the priorities. 

Three main groups of scrap and their causes

A detail or material can be declared as scrap due to three main reasons:

  • Rejection in raw material form. This group includes scrap materials that were rejected due to spoilage, wrong transportation conditions, or wrong storage conditions. Sometimes, this group can also include materials that have shown off-specification performance characteristics during testing. In this case, the material cannot be processed further or add more processing value.
  • Rejection in partially processed form. Production processes often involve multiple steps to get the final detail, and the failure during any of them means that the part cannot take part in further production. This is the most common cause of scrap, and it accounts for the majority of cost losses.
  • Rejection in fully processed form. Some goods and parts can be declared as scrap after the production process is finished because they don’t meet the specification requirements. At this stage, one can make the scrapped parts into something usable by adding more labor or reworking the part.

As you can see, scrap can happen during any step of the manufacturing process, and it usually indicates some problems which cannot always be tracked visually. That’s why a modern facility should have the means of tracing the origins of the scrapped part and identify the causes of production deviations.

How to identify and deal with scrap?

When it comes to managing waste, some project methodologies, such as Lean Six Sigma, have already developed the strategies directed at reducing waste and repurposing the scrapped details that are already happened.

Most common methods of scrap management could be broken down into two groups:

  • Preventive methods: data and production monitoring, preventive maintenance, and process optimization.
  • Root cause analysis: facility audit, improved training sessions for shop workers, management change, review of material sourcing, etc.

Preventive methods include using software that can help you automate certain operations, such as data collection, equipment monitoring, and employee training. 

For example, AGW Quality module helps you to declare scrapped parts or details in a few simple steps, and uses tools like heat maps to specify the repeated defects, so you can pinpoint the exact cause.

You can also specify the cause of scrap and store the data in the system, which allows you to use the AGW reporting tool and create detailed diagrams that show your progress in waste management and the changes in scrap rate. 

Analyzing reports will help you identify the root cause of high scrap rates and optimize the production process. Depending on the cause of the high scrap rate, you can choose one of the following optimization scenarios:

  • Obsolete equipment: conducting an in-depth facility audit and identifying the exact production capacities. Upgrading the equipment or optimizing the workflow using current capacities.
  • Human factor: conducting training sessions for shop workers and skill reassessment. Including learning sequences in order to achieve the needed level of skills, or adding learning sequences using AGW checklists or documentation features.
  • Low-quality materials: reviewing material sourcing.