Thermal & electrochemical deburring

Smoothness and precision are two critical firearms properties, so advanced deburring technologies prove especially valuable where hidden burrs pose a significant challenge. Slides, upper receivers, gas blocks, and bolt carriers benefit from thorough, efficient burr removal, ensuring flawless performance of the finished products.

When traditional machining methods fail to eradicate all burrs, industries often resort to manual deburring, vibratory methods, and brushing processes. However, each method brings its own set of challenges.

• Manual deburring requires skilled labor, adding a burden to the process
• Vibratory and brushing methods may struggle with detecting and removing hidden burrs, particularly in holes and breakthroughs finishing upper receivers, gas blocks, and bolt carriers

By adopting thermal deburring (TEM) and electrochemical machining (ECM) for firearm parts, manufacturers can elevate quality, enhance productivity, and ensure their parts’ reliability, safety, and performance.

TEM for firearms parts

TEM offers a swift and comprehensive solution to burr-related issues in gun parts. TEM ensures burr removal, prevents jams, and enhances overall smoothness of firearms parts.

TEM ignites a pressurized mixture of combustible gas and oxygen within a sealed, controlled chamber. This ignition produces intense heat energy, reaching temperatures between 2,500°C and 3,500°C for milliseconds. Methane has good energy content by volume and is the most common fuel gas used for thermal deburring. It may be supplied technically pure in bottles or through natural gas networks.

The sudden release of extreme heat causes burrs and flashes to catch fire, burn in excess oxygen, and vaporize until the heat dissipates into the body of the workpiece. The result is precise removal of burrs, leaving behind clean gun parts and ensuring optimal functionality.

TEM steps

1. Components are loaded into the TEM chamber, the chamber is closed
2. Chamber is filled with a pressurized mixture of gases
3. Gas is ignited
4. Burrs are oxidized, component is deburred
Chamber is vented to depressurize
5. Chamber opens, and components are unloaded

Benefits of TEM

Speed –Because burrs or flashings are much smaller than the component, they reach their auto-ignition point instantly. The burrs oxidize in the oxygen-rich chamber without harming the component.

Integrity – The smallest geometries concentrate the heat and burrs slightly attached to the components and particles are vaporized.

Reliability – Compared to manual deburring, the operation is guaranteed to reach every component area, inside and out.

Low cost per part, increased productivity – TEM removes the burden of finding skilled labor by relying on a machine. In the firearm industry, the TEM machine usually deburrs multiple parts at the same time. The chamber and fixture design, combined with the optimized number of parts, will reduce the gas volume and the cost of each load. With a cycle time of around one minute, high volume is no longer an issue. The machine can be automatically loaded and unloaded.

Firearms components deburring with ECM

ECM is usually the static version of electrochemical machining technology, unlike EC rifling, which leverages a dynamic version of the ECM process presented in the April/May 2024 issue of Defense and Munitions. In the ECM static variation, the cathode moves through the target area before the current is applied. The cathode will return to standby right after the ECM machining operation. It cleans gun breeches by eliminating burrs and particles in multiple areas simultaneously while enhancing machining efficiency by providing clean firearm components in 60 seconds.

The ECM process operates based on Faraday’s law of electrolysis. According to this principle, the mass of a metal dissolved is proportional to the quantity of electrical charge transferred to the electrode.

ECM leverages the dissolution of material through controlled electrochemical reactions, allowing for precise and targeted removal of burrs from firearm components.

Depending on the specific requirements, ECM can be employed for simple deburring or deburring combined with edge shaping.

ECM steps

1. Components are loaded into the ECM open fixture; top side of the fixture is then closed on the bottom one, surrounding the part
2. Electrolyte starts to flow; short circuit test takes place before applying the total current
3. Full current runs, controlled by cathode or cathode groups
4. Burrs are dissolved, edges are rounded, shaped, and structure applied
5. Cycle finishes; fixture opens
6. Components are unloaded

ECM benefits

Target process – When design accuracy drives finishing accuracy, ECM is the answer. The paradigm is selective areas and selective types of finishing for each location.

Increased life span – ECM deburring/radiusing removes stress risers, enhancing the component’s longevity.

Precision – The process is entirely under control, and the high efficiency achieves superior deburring or edge rounding within stringent tolerances.

Productivity – The ability to process multiple areas within a part at once and numerous parts simultaneously combined with a cycle time of around one minute enhances productivity.

Quality – Deburring, edge-breaking, and edge-rounding quality won’t depend on a human factor. Day after day, batch after batch, part-to-part results are guaranteed.

Thermal deburring and electrochemical machining represent a paradigm shift in firearms manufacturing. They address challenges associated with traditional methods and introduce efficiency and precision into the process.

Post-treatment

TEM and ECM require pre- and post-treatment. During pre-treatment, the components should be free of chips and contaminants, such as oil. For post-treatment, dunking stations are typically used for cleaning and passivation. Cleaning agents contribute to a finished product ready for assembly.

TEM and ECM highlights

Deburring effectiveness – TEM eliminates burrs, flashings, and loose particles, regardless of their location on – or inside – the component. ECM provides target deburring with edge shaping, nice radius, or specific geometry.

Process efficiency – TEM and ECM leave a clean surface, free of burrs and left particles.

Ease of use– TEM requires a simple fixture to hold and secure the firearm’s components. ECM doesn’t involve complex tooling but simple cathodes, keeping running costs reasonable and below manual cost. For ECM and TEM, part handling is easy and quick.

Blockage elimination – TEM and ECM are non-contact processes; burrs and flashings can’t be folded or pushed onto the component.

Final process – Compared to manual and mechanical methods, TEM and ECM don’t generate secondary burrs, and there’s no risk of scratching critical areas.

High production rates – Multiple parts within a 60-second cycle time is typical, and 24/7 operations are achievable.

Cost-effectiveness – TEM processing costs are less than a fraction of a cent for gas and electricity use per component, resulting in low operating costs. Compared to solutions providing deburring and edge shaping, ECM operating costs are among the cheapest.

Quality and repeatability – Superior process stability and reasonable process control ensure precision, consitent quality, and high repeatability.

Ease of automation – TEM and ECM equipment always come with pre-integration features, making automation an easy next step to further increase productivity.

TEM and ECM can significantly support the improved performance of firearm components, minimizing failures and warranty claims, leading to higher customer satisfaction.

Extrude Hone https://www.extrudehone.com

About the author: Bruno Boutantin is market & business development director for Extrude Hone Group.