In this month’s “Six Questions” feature, we’re speaking with Winn Henderson, UL Consumer Technology Senior Staff Engineer, about Laser Safety in Additive Manufacturing (AM). Winn speaks to the risks and hazards associated with lasers, considerations for AM equipment, and the certification measures that can be taken to meet the necessary product safety standards.

#1 What are the potential concerns from lasers used in Additive Manufacturing?

Typically, a high powered hazardous laser is employed inside the product to assist with the additive manufacturing process.  These lasers can burn skin, cause eye damage, and cause fires if they are directed onto certain materials.  However, typically, access to this high powered radiation is not required for the product to perform its intended function, and therefore the laser radiation should be fully contained by a suitable enclosure.  Also, any panels or doors that can be removed or opened to gain access to the laser processing area should be interlocked to shut the laser off.

#2 How is the potential hazard from a laser identified?

Lasers are classified from Class 1 (least hazardous) to Class 4 (most hazardous) with sub-classes in between.  For a laser product in general, access to laser radiation over Class 1 is only acceptable when access to that radiation is necessary for the product to perform its intended function.  For AM, typically, operator access to the high-powered (i.e. Class 4) laser radiation inside is not necessary to use the product, so the laser should not be accessible during operation.  In this instance, with a suitable enclosure, the product could be considered a Class 1 laser product (based on operator access) with Class 4 internal laser radiation (may be accessible to trained service personnel).

#3 What types of safety standards are applicable to address laser product safety of Additive Manufacturing equipment?

In the US, the CDRH (Center for Devices and Radiological Health – a branch of government under the FDA) regulates all laser products sold, marketed, or imported in the US.  Manufacturers are required to evaluate the laser products to the 21 Code of Federal Regulations (CFR) Parts 1010 and 1040, and file a specific laser report template with the CDRH.  Outside the US, the laser product safety requirements are contained in IEC 60825-1.  Both of these standards provide requirements for construction features, labeling, and user manual statements depending on the laser power and laser class that is present.  It should be noted that the CDRH accepts some portions of IEC 60825-1 in an attempt to harmonize with the IEC requirements.

#4 What is the basic process to evaluate an Additive Manufacturing product to these laser product safety standards?

The laser power is determined at each location in the product that may be accessible during conditions of operation, maintenance, and service.  Methods for measuring the laser power are described in the standards (CDRH 21CFR and/or IEC 60825-1).  Then, these laser powers are compared to limits in the standards to determine the laser class at each location.  Knowing the laser class at each location then allows one to determine the applicable labeling, construction features, and user manual statements that are required to protect the operator, maintenance, and service personnel.  Typically, the final task is to create a report (CDRH Laser Product Report or IEC 60825-1 Report) to document how the product complies with the requirements.

#5 If a laser component or sub-assembly is already certified to the laser product safety standards, is there a need to do anything else at the end-product level?

Yes.  A laser component or sub-assembly may be classified as a Class 4 laser, but the access to this laser radiation should typically be prevented in the final product during operation.  Therefore, an evaluation is conducted at the end-product level to check this accessibility.  Also, the laser product safety standards contain end-product labeling, construction features, and user manual statements that would not be addressed on the final product if there is only reliance on a component or sub-assembly evaluation.

#6 How can UL assist with evaluating Additive Manufacturing products to the laser product safety standards?

UL can perform both CDRH and IEC 60825-1 laser evaluations on Additive Manufacturing products.  The CDRH evaluation provides a ready-to-file CDRH Laser Product Report that can be sent to the CDRH to document compliance with the requirements and meet those obligations.  The IEC 60825-1 evaluation provides a report in the formal IEC Test Report Format that also documents compliance with those requirements.  Some manufacturers may only need assistance with determining if the laser radiation is contained in the final product configuration – UL has tailor-made services that may involve performing the testing and a construction review, then providing the results in a letter report.  There are other options also, such as the Laser Verification Mark Program for manufacturers that may want to make a specific claim alongside a UL Mark that there is no operator accessible radiation.

To learn more about UL’s Laser Safety Services

 

About Winn Henderson

Winn Henderson received his B.S. in Electrical Engineering in 1997 from North Carolina State University in Raleigh, North Carolina. He has worked at UL for the past 21 years in the field of Optical Radiation product safety (laser/LED/lamp radiation) and is based in Research Triangle Park, NC.

In this role, Mr. Henderson is heavily involved in the laser product safety requirements contained in FDA/CDRH 21CFR, the IEC 60825 series of Standards, IEC 62471, RP-27, and others. Mr. Henderson is UL’s Subject Matter Expert and serves in the Primary Designated Engineer role at UL for Optical Radiation Safety. He evaluates laser products to the laser safety Standards, develops global UL guidelines on addressing laser product safety, and sets up Optical Radiation Laboratories globally within UL.

He is also an active member of the International Electrotechnical Commission (IEC) Technical Committee (TC) 76 for “Optical Radiation safety and laser equipment”, as well as the IECEE CTL Expert Task Force (ETF) 11 for Lasers. On ETF11, Mr. Henderson also serves as a Technical Advisor for the Proficiency Testing Program.


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