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CNC Machining Services
Get precision CNC acrylic parts for optical, medical, and industrial applications, machined to tight tolerances without stress cracking.
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FastPreci produces custom acrylic parts from single prototypes to full production runs with no minimum order.
We machine flat parts on 3-axis centres and complex geometry on 5-axis centres.
Cylindrical parts such as tubes, rods, lens blanks, and housings are turned on precision lathes.
We use drill bits designed for plastics with the correct helix angle and geometry for acrylic machining.
Drills cut cleanly and clear chips without building heat at the hole wall.
Standard metal drills are never used on acrylic.
Thread engagement depth reviewed during DFM to prevent fracture under load.
Bevels, chamfers, and radiused edges on display panels require specific tool paths.
Entry and exit transitions are individually programmed per part geometry
Achieves consistent edge quality across full production runs.
Acrylic cracking is typically caused by three factors: cutting heat, unsuitable coolants, and residual stress after machining. These issues are process-related rather than material defects. We eliminate them through a controlled machining protocol.
We use single- and double-flute carbide tools designed for plastics to minimise heat buildup and prevent chipping, delivering cleaner cuts than standard metal-cutting tools.
We run spindles between 12,000 and 18,000 RPM. Feed rate is reduced at internal corners and edges. Corners are vulnerable to chipping in acrylic, and slower feed at those transitions prevents it.
Only compressed air and light mist are used. Flood coolant is avoided. Chlorinated or unsuitable coolants can cause solvent stress cracking, where parts fail later under low load. Air cooling fully eliminates this risk.
After machining, parts with thin walls or tight tolerances are placed in an oven at 70 to 80°C for several hours. This process releases internal stress that builds up during cutting. For parts, annealing is a standard step.
Important dimensions are checked during machining using calibrated gauging. When deviations are detected, corrections are applied before continuing the process, ensuring consistent batch results.
Our machining facility is maintained at controlled temperature to minimise thermal variation. Acrylic stock is conditioned before machining to ensure dimensional stability throughout the process.
A freshly machined acrylic surface has visible tool marks and light surface haze. The right finishing method depends on the part geometry and the clarity level your application requires.
Method | What It Does | Best For |
Diamond Turning | Single-point diamond tool cuts to sub-micron surface finish | Optical flats, lenses, precision windows |
Progressive Sanding | Graded abrasive from 400 to 2000 grit removes tool marks | Flat face preparation before polishing |
Buffing and Polishing | Rotary cloth with polishing compound produces high clarity | Edges and external faces |
Vapour Polishing | Solvent vapour reflows the surface layer to remove haze | Internal bores, channels, and complex shapes |
Flame Polishing | Uses a hot torch to melt the surface layer, producing a clear transparent finish | It works best for clear plastics like acrylic, especially curved edges and internal holes |
As-Machined | Deburring only, no surface treatment | Internal parts and non-visible faces |
For optical parts, we recommend specifying the required surface roughness value in your drawing rather than a finishing method. We select the process that reaches your specification at the lowest cost.
Acrylic walls below 1.5 mm may deflect during machining. Unilateral tolerances are recommended over bilateral tolerances. Fixturing is confirmed before production to ensure stability during cutting.
Stress relief annealing at 70–80°C may cause minor dimensional changes. For tolerances tighter than 0.03 mm, parts are machined with compensation offsets and measured after annealing when required.
Acrylic interfaces are prone to stress cracking under contact load, especially near holes and press-fit areas. A minimum clearance of 0.1 mm is recommended between acrylic mating surfaces.
Direct tapping into acrylic requires a minimum thread engagement of 2.5× diameter. Coarse threads are preferred as they distribute load more effectively than fine threads.
The acrylic grade affects machinability, performance, and stability. Choosing the wrong grade is one of the most common and costly mistakes in acrylic projects.
The preferred grade for precision and excellent work. Cast acrylic has a more uniform molecular structure than extruded sheet.
Machines with less residual stress and lower fracture risk
Polishes to higher clarity than extruded material
Suitable for flat covers, machine guards, and display panels where dimensional consistency is important then smooth finish.
Tighter thickness tolerances than cast material
Requires reduced feed rates to manage stress cracking risk
Standard PMMA yellows under prolonged sunlight. UV-stabilised grades are specified for outdoor applications.
Maintains seamless clarity for ten or more years under direct sunlight
Correct choice for outdoor enclosures, architectural panels, and signage
Used in applications requiring controlled light transmission, glare reduction, and maintained optical clarity.
Reduces glare and UV exposure for protective windows and covers
Maintains consistent color and optical performance across the part
Provides a diffused surface finish for applications requiring soft, uniform light distribution.
Scatters light to eliminate hotspots and improve visual comfort
Matte surface reduces visibility of scratches and surface imperfections
Designed for applications that require enhanced light guidance and edge illumination.
FastPreci delivers CNC acrylic components for demanding industries where precision and clarity are critical.
We produce biocompatible acrylic parts for clinical and diagnostic systems.
We machine UV-stable acrylic parts for electronic enclosures and display assemblies.
Electronic enclosures with tight form-fit tolerances
Display panels with clean edge finish
Instrument housings requiring internal visibility
Connector and switch covers for industrial assemblies
Our machining ensures tight tolerances for high-precision testing and assembly fixtures.
Precision fixture bodies for wafer handling
Chemical-resistant housings for wet-process equipment
Transparent covers for process monitoring
We produce durable acrylic parts for industrial inspection and automation systems.
We machine high-clarity, chemical-resistant acrylic parts for laboratory testing and diagnostic tools.
We machine high-clarity acrylic parts for optical systems and light distribution.
FastPreci holds ISO 9001:2015 certification. Our quality process for acrylic parts covers dimensional inspection, visual inspection, first article reporting, and material traceability.
Each part is examined under controlled lighting for surface cracks, tool marks, chips, and any cloudiness that indicates subsurface stress damage. For production orders, we machine and fully inspect the first part before the rest of the batch proceeds — the inspection report is available before we continue production.
We keep batch records for all acrylic stock used in production. If a material quality issue is identified, we can trace every part made from that batch.
For clear plastic CNC cutting, acrylic outperforms polycarbonate and glass on machinability, weight, and long-term clarity.
Property | Acrylic | Polycarbonate | Glass |
Light Transmission | 92% | 88% | 92% |
Impact Resistance | Medium | Extremely High | Low, shatters |
Machinability | Excellent | Good | Very Difficult |
UV Resistance | Excellent, no coating needed | Requires UV hard-coat | Excellent |
Weight | 1.19 g/cm³ | 1.20 g/cm³ | 2.5 g/cm³ |
Scratch Resistance | Moderate, can be coated | Lower than acrylic | High |
Long-Term Clarity Outdoors | Stable | Yellows without protection | Stable |
Machining Cost | Low to medium | Medium | High |
Lead times as fast as 3 business days. We accelerate your R&D and production cycles, helping you meet tight project deadlines without compromising quality.
Tolerances as tight as ±0.02 mm on optical features. Leveraging 5-axis machining and process-specific tooling, we consistently meet tight dimensional requirements on clear plastic parts.
Deep knowledge of acrylic grades including cast, extruded, UV-stabilised, and tinted PMMA. We understand how different grades behave under machining stress to ensure crack-free results.
Our precision plastic machining setup uses spindle speeds, feed rates, and coolant selected specifically for PMMA machining.
ISO 9001:2015 certified. Our QA process includes dimensional and visual inspection under controlled lighting, first article inspection, and full material traceability available upon request.
Every project undergoes a formal Design for Manufacturability review at no additional charge. We identify fracture risk, tolerance issues, and process constraints before the first cut.