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Lean manufacturing in laser marking: How to improve the marking workflow?

Summarizing a recent webinar, held by FOBA’s Dr. Faycal Benayad-Cherif and hosted by Regional Sales Leader Jeff Kniptash, the following article is giving an overview of what lean manufacturing means in industrial laser marking.

There are various approaches when implementing a lean laser marking workflow, however it is mainly a question of defining which technology can simplify as well as streamline and speed up the process. In laser marking this usually has to do with integrated vision and automated mark alignment.

What is lean manufacturing?

Lean manufacturing is a production related process improvement programme to drive organisations towards cost reduction, strategic positioning for advantage, improved quality and profitability.

According to the “Toyota Way”, a well-established continuous improvement concept for lean manufacturing, the main focus is on

  • Managing just-in-time inventory
  • Automated quality control
  • Preventing waste.

Waste in this context means any activity or outcome that does not add value. There are seven kinds of waste according to the Toyota definition: 

  • Defective products
  • Waiting time: inactive working periods due to delays in the workflow
  • Unnecessary transportation of goods and of people
  • Avoidable motion: try to optimize process first to avoid unnecessary procedures
  • Over-processing of parts beyond given standards
  • Inventory that is waiting and taking space
  • Overproduction

All these kinds of waste produce downtime. When considering human activity in the manufacturing process, one could additionally mention the fact that also non-utilized talent is another kind of waste, as human skills could possibly add more value in a different setting or with different tasks.

It is mainly the first four of the above wastes that have to be taken into account for a lean project in laser marking (defective products, waiting time, unnecessary transportation, avoidable motion).

What is lean manufacturing in industrial laser marking?

Most laser marking applications represent the last step in the manufacturing process before the final packaging of the product. Sometimes, as in the medical industry, there are also cleaning, passivation or disinfection steps that follow.

Laser marking is of special importance as it adds value to the product or, in the worst case of marking mistakes, makes a product unmarketable. Lean manufacturing in laser marking therefore implies automated processes that prevent errors, guarantee quality, and thus avoid waste.

Considering the seven kinds of waste mentioned before, in the context of laser marking the most relevant wastes to prevent are

  • Part defects
  • Waiting time
  • Unnecessary transfer of goods or people
  • Over- or extra-processing above the required standards

An integrated vision system in the laser marking technology has proven to be of great benefit or even a prerequisite for lean manufacturing. The camera provides a direct view on the part to be marked, and the according software makes it possible to achieve a certain degree of automation in the process. It can even make certain extra steps obsolete like validating the part size and making sure the part is not already marked. The result is an improved production yield and reduced part processing time.

What does a lean laser marking process look like in manufacturing practice?

Example from the automotive industry

Considering a case from the automotive industry where a steel braking component needs to marked with a data matrix code: An operator places the part in the laser marking machine and the part gets marked (12 seconds), removes the part and carries it to another station to inspect the data matrix code (20 seconds). Assuming the travel time between stations takes 15 seconds, the entire process takes a total of 47 seconds per part.

 

There are three wastes to be optimized or prevented:

  1. The waiting time of the operator in between the marking and the inspection
  2. The transportation of the parts between the marking and the inspection stations
  3. The extra processing (avoidable motion) of human-operated code inspection in an extra station

The solution

... is to achieve the following by means of a vision-assisted marking system:

  • The elimination of unnecessary operator's movement between the laser and the inspection station thanks to a closed-loop workflow solution built in the machine
  • A fully integrated code validation: The validation software reads back machine-readable codes and verifies the laser marked content. Possible errors will be indicated on the user interface.

This workflow takes a total of 12.5 seconds per part, including loading and laser marking (12 seconds) and only 0.5 second of mark inspection. Compared to the previous system, this means time savings of nearly 75 percent.

Example from the medical industry

Another common example from medical device manufacturing would be the marking of a titanium or plastic implant with a UDI code (Unique Device Identification). The UDI code consists of a human and a machine-readable part, which both need to be inspected to guarantee the required marking quality. In addition to the three wastes from the previous example, in this case there is a fourth source of waste to be considered:

1. Assuming that the implant must be inspected before and after marking there is even more waiting time for the operator:

  • During pre-mark inspection to prevent the marking of the wrong part, of a part that already has been marked or that bears defects
  • During the text visual inspection under the microscope (60 seconds)
  • During the 2D code inspection in a verifier station (60 seconds)

2. Creating defective parts will be avoided through a pre-mark inspection that makes sure a wrong part will not be marked. Due to laser auto-correction, marking by mistakes will be prevented. However, if there is an incorrect mark, the post-mark inspection system detects mismarked parts and prevents them from being processed further.

3. Transfer time of parts from one station to another as well as in and out of the laser marker is extended due to three different stations. With one single station for the entire process this can be prevented. 

4. Extra processing of a part is no longer necessary but happens in one flow. The marking steps within the laser marking station include both the automated alignment of the mark and the validation (pre- and post-mark) of the parts and marked contents.

The solution

... for the creation of a lean laser marking process is based on the following features of FOBA’s integrated vision:

 

  • Mosaic: a marking functionality that enables the automated and precise alignment of the laser mark relative to the part, even if the part is placed randomly in the marking field.
  • Optical Character Verification OCV: The integrated camera reads back the text and checks if the intended content is correct.
  • Code Validation: The system also checks the code quality and grades it according to required standards.

What are the first steps when approaching lean manufacturing?

Timely planning and advice from experts with lean experience is of great help when starting to implement a lean laser marking process. Due to continuous development on the market, it is always important to think out of the box and to be willing to try new ways of manufacturing. This includes the consideration of robotic solutions for the automation of parts handling as well as the installation of advanced vision and inspection tools.

It is important to involve an entire management team and additional coaches and expertise wherever necessary. A lean project also needs an according measurement matrix to monitor and evaluate how things are proceeding. It may require some time to turn a project into a lean project. The actual duration depends on the complexity of the project and might take approximately six to twelve months.

What are the overall benefits of lean manufacturing?

Once the elimination of waste has successfully been implemented to streamline a process, this will bring several benefits:

  • Add value to the customer or final product
  • Save costs through the reduction of time and material
  • Encourage and challenge innovation and constant improvement
  • Help reduce environmental impact

Contact us at info@fobalaser.com and let us help you to streamline your laser marking workflow!