JLCCNC Blog

Surface Finishing Processes

Blackening Coating: How It Works, Types, and Applications

Key Takeaways Blackening coating is a broad category of dark metal surface treatments, while black oxide is a specific conversion coating. Conventional hot black oxide on steel forms a thin magnetite surface through an alkaline oxidizing process. Cold blackening uses different chemistry and should not automatically be treated as equivalent to hot black oxide. Black oxide has minimal dimensional impact and can reduce surface reflectivity. Corrosion protection depends heavily on the sealing treatment an......

Sep 24, 2026

Plastics for CNC

Acrylonitrile Butadiene Styrene: Properties, Types, and Applications

Key Takeaways ABS can provide useful service performance at moderately elevated temperatures, with the actual continuous-use and heat-deflection limits depending on grade, loading, and service conditions. It's an amorphous terpolymer whose properties come from the combination of three monomers: acrylonitrile contributes chemical resistance and stiffness, butadiene provides impact toughness, and styrene gives the material its processability and surface finish. ABS plastic provides moderate heat resista......

Sep 24, 2026

Industry Use Cases

Custom Bicycle Parts: CNC Machining Guide

Key Takeaways CNC machining is often a practical choice for custom bicycle parts when production quantities are low, the geometry is complex, or critical interfaces require tighter dimensional control than near-net-shape forming can provide. The parts that benefit most are the ones where fit accuracy genuinely matters, such as bearing seats, bottom bracket interfaces, derailleur mounting features, and suspension pivots, where dimensional variation can affect assembly and performance. For CNC-machined ......

Sep 24, 2026

Design Tips & Best Practices

GD&T Runout: Definition, Symbol, Measurement & Tolerance

Key Takeaways Runout limits surface variation while a part rotates around its specified datum axis. The datum feature establishes the axis used for the runout requirement. You compare the full indicator variation during rotation with the tolerance stated on the drawing. Circular runout applies at individual circular sections of the controlled surface. Total runout evaluates the controlled surface across its specified extent. Runout is not a size tolerance, and its value is not determined by the diamet......

Sep 24, 2026

Design Tips & Best Practices

GD&T Perpendicularity: Definition, Tolerance & Examples

Key Takeaways Perpendicularity is an orientation control used for a feature specified at 90° to a datum. A surface callout controls the complete surface within two parallel planes set perpendicular to the referenced datum. An axis callout controls the derived axis inside the specified tolerance zone instead of controlling the physical surface directly. Perpendicularity does not establish the location of a feature. A drawing can require another geometric control when position also needs definition. Dat......

Sep 24, 2026

Plastics for CNC

Polycarbonate CNC Machining: Properties, Design Guidelines, and Manufacturing Considerations

Key Takeaways About Polycarbonate CNC Machining Polycarbonate is used for clear guards, covers, housings, and inspection parts where visibility and protection matter in use, not just on drawings. Different machining materials or grades behave differently during cutting and show up mainly in surface clarity and edge condition. Heat from cutting affects surface marks more than the strength of the material itself. Thin walls and wide flat areas are where most surface issues start during machining. Tool s......

Sep 23, 2026