Adding “Introduction to Thermal Spray” to the Welding Curriculum
Plasma Powders and Systems, Inc.
Richard S. Brunhouse, Peter Foy, Dale Moody
Thermal Spray in a welding curriculum? What does a coating technology have to do with a joining technology?
Yes, there are differences. A welding “gas torch” is a
thermal spray “gun”, a welding “stick” is
thermal spray “wire”. However, there are many commonalities between welding and thermal spray. They use the same energy sources: acetylene, propane, hydrogen and electricity. Both use heat to melt or soften and combine materials. Part manipulators for both range from a simple lathe to an eight-axis
robot/turntable system. Welding and thermal spray require similar chemistry skills along with similar math skills for calculating deposit rates, efficiencies, etc. Also, thermal spray and welding share identical OSHA issues: personal protection from fumes, acoustics, heat and light, etc.
Thermal spray is an essential partner with welding technology. Consider the welding of galvanized piping for a highway overpass or school yard fencing. Rust stains on adjacent concrete could mean the welding did not provide the corrosion barrier needed and that the welded area should have been over-sprayed with zinc to protect it from the environment.
The AWS Mission statement reads: “The Mission of the American Welding Society is to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying.”
To solidify and strengthen that mission, the 65-year-old International Thermal Spray Association became a Standing Committee of AWS January 1, 2012. Therefore, thermal spray training is certainly appropriate for a welding school.
The purpose of an Introduction to Welding is to teach welding types and fields in which welding can be successfully used and to educate the architect/engineer in the techniques available to enhance their designs.
HISTORY AND BACKGROUND
For the last 30 years, there have been many thermal spray advances in technology: thermal barrier coatings for high performance jet engines and gas turbines, porous ceramics for prosthesis bonding and specialty stealth coatings for military applications, to name just a few. As with any new technology that has competing processes, choosing the right one is dependent on what worked in the past and whether or not there is time to look for a new alternative.
The Thermal Spray Society (TSS) has been the leading source for thermal spray technical information for many years. Most of the information weighs toward the technical reasons a coating will perform in a given way based on a given set of circumstances. Frequently, it is still necessary for a thermal spray shop to develop their own methods of applying this knowledge to their business segments. Contrast this omission to the AWS charter where the application of technology is emphasized. Accentuating this point, the AWS C2 Subcommittee on Thermal Spray is more geared towards the application of the technology.
An internet search on “Welding Training” results in a myriad of local schools offering various welding programs. This is in contrast to the results of a search on “Thermal Spray Training” that yields listings of training programs in India, China, England and Switzerland; few are in the U.S. Much more is needed to demonstrate that choosing a job in the thermal spray industry is a wise career choice.
While thermal spray should be promoted as a technology career move, it is often overlooked. An internet search on “Job Corps welding” locates a detailed Job Corps document which promotes welding as an “Advanced Manufacturing Career Pathway”. The various subject areas covered are detailed as are eligibility requirements and an explanation of the credential offered. However, a search on the U.S. Government’s “Careeronestop” website which references a “Certified Thermal Spray Operator” program links to a page that is no longer active.
In preparation for this article, Plasma Powders and Systems, Inc. conducted a survey of its customer base. The intent of the survey was to characterize the thermal spray training presently available and to identify where needs existed. The results of this survey were very interesting. For example:
Over ninety percent of the companies responding to the survey rely on in-house training, i.e. everybody is doing their own thing. Thermal spray training lacks uniformity.
Over eighty percent of the companies use multiple forms of thermal spray, usually including
wire arc along with plasma followed by
combustion powder and
HVOF. Any training needs to cover multiple thermal spray processes.
Most companies indicated a critical need for operation and maintenance training with some need for laboratory and shop management. A smaller number indicated a need for specialized training for military or medical thermal spray operations.
One shop expressed frustration in seeking out trained individuals stating it is “very difficult to find employees with skills needed to become spray operators. We understand that there are very limited numbers of experienced operators available, but it's difficult to even find workers with basic skills in the trades.” Another noted that there is a need for “training on the basics regarding surface preparation, handling, grit blasting techniques and masking techniques.” These are issues similar to those found in welding operations.
As a start, Thermal Spray needs to be included in an “Introduction to Welding” class. A welder should understand the principles of thermal spray as the welder could be working right next to a thermal spray operator or may be one and the same at some point in their career.
As these two technologies share much in common, there should not be a need for separate courses on safety, OSHA standards, basic math, etc. The curriculum for Introduction to Thermal Spray should include terminology, an overview of thermal spray applications, a discussion of thermal spray systems and associated and ancillary equipment, a summary of inspection and quality control techniques, the costs of alternatives and certification. The following outline presents a curriculum that might be adopted as part of an Introduction to Welding.
1. Thermal Spray Overview: What It Is
3.1. Around the Home
4. Processes (with comments on the gun, material feed and power control along with relative start-up and operating costs)
4.1. Combustion Powder
4.2. Combustion Wire
4.3. Electric Arc
5. Ancillary Equipment
5.1.2. X-Y Units
5.2. Hoods and Rooms
5.3. Dust Collectors
5.4. Safety Systems
6. Quality Control
7. Process Specification
8. Operator Qualifications
is an important issue for most thermal spray shops. Offering a program that allows for uniform training and qualification of knowledge and skill is very important. The AWS C2.16 Guide for Thermal Spray Operator Qualification program has been in existence for a long time and its guide is currently being updated to include the latest thermal spray processes and techniques. It is similar to the certification program for welders. This is just a start.
Consider the certification programs for welding. These are:
QC1 Standard for AWS Certification of Welding Inspectors
QC4 Standard for Accreditation of Test Facilities for AWS Certified Welder Program
QC5 AWS Standard for Certification of Welding Educators
QC6 AWS Standard for Certification of Welding Technicians
QC7 Standard for AWS Certified Welders
QC13 Specification for the Certification of Welding Supervisors
QC14 Specification for the Certification of Welding Sales Representatives
QC15 Specification for the Certification of Radiographic Interpreters
QC17 Specification for AWS Accreditation of Certified Welding Fabricators
QC19 Specification for AWS Certification of Robotic Arc Welding Personnel
Eventually, equivalent certifications should be available for a thermal spray operator if the demand by industry for such a program is required. It is possible that some of these existing specifications could be adapted to thermal spray by replacing “welding” with “thermal spray” and making a few other minor changes. Both industry and the training institutions would support this effort if there is an obvious demand for certification and it meets the economic model for such a program to be instituted.
For now, it is recommended that an Introduction to Thermal Spray be added to the curriculum of any Introduction to Welding classes. This can be completed with less than sixty Power Point slides and in less than one hour. There are a number of thermal spray suppliers that have material readily available. For example, Plasma Powders and Systems, Inc. has a generic presentation that they have made available to the local trade schools. (email@example.com)
As an educator or a student, make sure that thermal spray is now included in the welding curriculum of your trade school.
To request the free publication "What Is Thermal Spray?" from the International Thermal Spray Association, send an email with the quantity required and mailing information to