Foreign Object Damage in Heat Treatment (FOD)

As customers, especially aerospace, defense and automotive, require more frequent cosmetic and contamination-free heat treatment, heat treaters need to think more about FOD (foreign object damage). So what is this FOD ?

Before we start, I think I should specify some definitions. For this, I will quote the relevant aviation standard AS 9146 .

What is Foreign Matter ( FO)?

Any foreign matter or object that could potentially enter the product or system and/or become FOd and potentially migrate into the product or system (e.g., hand tools, consumables, hardware, product protective packaging, personal jewelry, product processing residues, and environmental debris) is not removed and if left uncontrolled will cause FOD. Reference 9146; Section 3.3

What is Foreign Object Debris ( FOd)?

Any FO that enters and/or is transported into the product or system and could potentially cause FOD if not removed and controlled. Reference 9146; Section 3.5

What is Foreign Object Damage (FOD)?

Any damage attributable to FOd, expressible in physical or economic terms, that could potentially impair the required safety and/or performance characteristics of the product or system. Reference 9146; Section 3.4

Economic impact of FOD:

Internationally, FOD costs the aviation industry US$13 billion per year in direct and indirect costs. Indirect costs were ten times the value of direct costs, representing delays, aircraft changes, actual fuel costs, unplanned maintenance, and the like.

The aerospace industry has long been concerned about airport and flight deck ingestion issues and the FOD that technical crews can create during new construction and maintenance of aircraft.

Many industries serving aerospace equipment manufacturing are now experiencing concerns about what exactly goes into the production flow. This is also a particular concern for us heat treaters, because the high temperatures and reactive atmospheres used can cause insidious chemical damage to machined surfaces and direct mechanical damage to parts and furnaces.

How does FOD enter heat treatment facilities?

There are many ways for foreign materials to enter our heat treatment facilities and furnaces. I will write these below in the form of a few items.

Employee sourced

While working in the workshop, employee-induced FODs may occur in heat treatment facilities because they forget their personal belongings or the equipment they use in the furnace or while preparing the furnace charge.

• Jewelry, clothing, watches, personal protective equipment

• Hand tools, measuring equipment

Hand tools that can be forgotten while preparing the oven charge.

Customer sourced

Materials sent to heat treaters by their customers may also contain many different FODs. In my personal opinion, these are the most difficult group to recognize.

• Uncleaned burrs in machining

• Grinding, machining fluids, machining oils

• Products made of other materials that are indistinguishable in appearance mixed into the main batch. For example, aluminum parts involved in the steel heat treatment process.

• Polishing, deburring stones, packaging residues (wood, plastic, low-temperature melting metal) mixed between the heat-treated parts in the form of bulk (bulk)

• Fine sand grains remaining in the blind holes of parts that were sandblasted (glass ball) before heat treatment

• Parts painted for a reason, for example three-dimensional measurement.

Environmentally sourced

Even something as mundane as dust blown by wind through open doors can cause problems in heat treatment furnaces. For this reason, general cleaning is important, especially in facilities that perform heat treatments such as nitriding and nitrocarburization . Dust and dirt entering the oven hellhole must be controlled.

Another observation I have on this subject is about the creatures that inhabit heat treatment facilities, especially pigeons. Because it is hot, many creatures may choose to live in heat treatment workshops. Pigeon droppings can be found both on the ovens and on the items that have gone into the oven or are going to be baked.

Pigeon droppings on the oven door

I have seen mice haunt electrical panels before and cause problems there. Recently, I learned that a cat that hid in an aging (thermal) oven at an aluminum extrusion company died when the oven started working.

FOD Prevention

The best precaution against FOD problems is trained employees, both at the heat treatment facility and at the customer. All employees in the production chain should be made aware of FOD concerns and

Must be trained to recognize FOD.

According to AS9146, a good FOD prevention program should consist of 8 key elements:

• Program management (a system compatible with the PUKO cycle)

• Operations (anti-FOD thinking throughout the entire chain, starting from design)

• Area Designation (FOD areas divided into different levels)

• Training and Staff Access

• Product Protection (packaging, protected area, etc.)

• Clean and leave clean (clean-as-you-go)

• Supplies, Equipment, and Personal Items - Responsibility and Control

• Hand tools, Team Responsibility and Control

At the end of my article, I would like to share a sentence used by Lockheed Martin, one of the aviation giants, on the subject.

It's the smallest things that cause the biggest problems.

F-18 engine failure due to FOD on an aircraft carrier deck