Mold Textures in CNC Manufacturing(cam software Bernie)
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When designing a part, the CAD model will specify the overall shape but the surface texture is an additional attribute that can be added. While some textures are the natural result of the manufacturing process, often additional steps are taken to achieve a desired look and feel. This article will examine the role of textures, different methods for achieving textures, and some of the considerations when working with textured surfaces in CNC manufacturing.
The Role of Texture
Textures influence the visual appearance, feel, and performance of parts. Some examples where texture is important include:
- Grip surfaces - A rough texture provides friction for improved grip and handling. This is important for consumer products like tools, sporting equipment, and more.
- Appearance - Textures are added for aesthetic reasons on consumer products, architectural features, signage, etc. They influence light reflection and visual interest.
- Function - Precision surfaces like molds and dies often require carefully controlled textures to achieve proper performance. This includes directionality to the finish.
- Measurement and Testing - Reference surfaces with defined texture patterns are used to calibrate measurement equipment in quality control processes.
- Identification - Marker bands and identification features sometimes rely on specific texture patterns for easy recognition.
Due to this broad range of applications, being able to accurately and repeatably generate surface textures is very important with CNC.
CNC Texture Methods
There are several techniques that can be used on CNC machinery to impart textures onto parts:
Milling/Machining: Using traditional milling and machining, different cutters and approaches can create varied textures. Steps between passes, tool paths, stepovers, and cutter geometry all influence the final finish. Things like patterned tool paths, human artifacts, and intentional toolmarks can create identifiable textures.
EDM: Electrical discharge machining (EDM) alters material via electrical sparks. By controlling the process parameters, surfaces with controlled roughness or patterns can be generated through the erosive effect of the sparking action.
Laser texturing: Lasers can alter surface morphology through methods like laser etching, engraving, or texturing. The heat input causes micro-structural changes to selectively modify surface roughness. Different patterns and designs can be produced.
Media blasting: Blasting the surface with media like sand, glass beads, or other particulates provides a mechanical texture. Variations in media properties, blasting pressure, duration, and masking techniques allow control of the resulting finish.
Chemical texturing: Controlled chemical exposure like etching or anodizing can produce defined surface patterns as material is selectively removed or modified. This works for metals, polymers, and other materials.
Additive texturing: Additive techniques like 3D printing, spray coatings, or thick film layers allow physically building up texture onto a surface profile. Roughness, layer height, and droplet size of deposited material influences finish.
Regardless of process, employing CNC allows for programmed control over all the parameters influencing the texture. This includes things like depth, roughness, directionality, pattern, gradation, and more. The automated nature of CNC machining produces consistent, repeatable results.
Design Considerations for CNC Textures
There are some important factors to consider when designing and specifying surface textures in CNC work:
- Function – Determine what physical properties are needed from the texture for proper performance. This guides the selection of fabrication process and texture parameters.
- Accuracy and tolerances – Specifications should clearly define permissible variations in the texture for production quality control. This includes aspects like depth, roughness measurements, and pattern alignment.
- Measurement and inspection – Proper methods are required to verify texture during manufacturing. This may require specialized roughness measurement equipment. The means of qualification should be determined early on.
- Process capabilities – The production method must be capable of achieving the specified texture. Alternate processes should be explored if needed.
- Directionality – Some textures like grinding patterns rely on consistent directionality for functionality. Paths and orientation should be clearly defined.
- Transitions – Gradual changes in the texture may be required. The exact profile of texture gradients should be specified.
- Adjacencies – Interactions between neighboring textures may occur. Effects on the boundaries between textured areas should be considered.
- Repeatability – Process parameters for automated CNC texturing should be well defined to allow identical reproduction of the texture on multiple products or batches.
With careful planning and CNC programming, almost any conceivable surface texture can be manufactured. The automated nature of computer numerical control ensures these textures are generated accurately and consistently time after time. By considering the key factors around functional needs, measurement, capabilities, and design intent, surface texturing can be readily implemented even for complex geometries. With the precision available from CNC machining, intricate textures open up new possibilities for part performance and aesthetics. CNC Milling CNC Machining