Manual Polishing

Why Manual Polishing Remains Irreplaceable

Manual polishing does not represent outdated technology, but rather a process where the experience, tactile sensitivity, and judgment of skilled polishing technicians cannot yet be fully replicated by any existing machinery. It serves as the final - and most critical - bridge connecting precision mechanical machining with optical lens mold perfection.

Fundamental Reasons for the Existence of Manual Polishing

Compensating for Previous Process Defects

CNC machining leaves microscopic tool marks, while EDM creates a "pear-skin" textured surface. Though minute, these imperfections are directly replicated onto plastic lenses, causing light scattering, increased haze, and glare.

Achieving Ultimate Optical Surface Requirements

Optical lens mold cavities require mirror-like surfaces, typically with roughness values of Ra < 0.01 μm. Current CNC and EDM technologies cannot consistently achieve this level of surface finish directly.

Performing Deterministic Correction

Experienced polishers, using feedback from specialized equipment, can selectively and locally modify error-prone areas, bringing the mold geometry infinitely closer to the ideal optical design.

The Critical Role of Manual Polishing

Ensuring Optical Performance
Precise Control of Mold Geometry
Precise Control of Mold Geometry
Extending Mold Service Life

Ensuring Optical Performance

Manual polishing creates flawless mirror surfaces that guarantee optimal optical performance for LED lenses, minimizing light loss and scattering.

  • High Light Transmittance:Mirror surfaces significantly reduce light scattering and loss, ensuring maximum lens transmittance
  • Precision Imaging: Eliminates stray light, glare, and ghosting caused by surface defects, enhancing imaging contrast and clarity (MTF)
  • Beam Control: Perfect surface geometry ensures light converges or diverges precisely to the theoretical focal point, preventing spot distortion

Precise Control of Mold Geometry

Experienced polishing technicians can fine-tune mold shapes through selective polishing, ensuring each lens meets stringent optical design specifications.

  • Enables micro-adjustments to mold curvature radius and aspheric coefficients
  • Compensates for shape deviations introduced during previous processing stages
  • Guarantees every injection-molded lens conforms precisely to rigorous optical design standards

Enhancing Demolding Performance in Injection Molding

The exceptionally smooth mirror surface significantly improves the injection molding process, boosting production efficiency and yield rates.

  • The mirror-smooth surface substantially reduces friction between the plastic melt and mold cavity
  • Enables smoother lens ejection during demolding
  • Prevents defects such as mold sticking, stress whitening, and surface scratching, thereby increasing production yield and efficiency

Extending Mold Service Life

Professional polishing treatment not only enhances product quality but also significantly prolongs mold service life, reducing long-term production costs.

  • Well-polished surfaces exhibit minimal residual stress
  • Less prone to accumulating corrosive substances and plastic decomposition residues
  • Improves mold corrosion resistance and wear resistance

Manual Polishing Process

1

Preliminary Inspection

Utilize 3D scanners or interferometers to obtain mold surface data, comparing it with theoretical models to identify high points (excess material areas) and low points (insufficient material areas) requiring correction.

2

Rough Polishing

Employ coarse diamond compounds (e.g., W7, W5) to rapidly remove machining marks from CNC or EDM processes while initiating macro-shape corrections. Tools may include pneumatic hand grinders or specialized polishing machines.

3

Semi-Finish Polishing

Use medium-grit diamond compounds (e.g., W3.5, W2.5) to further reduce surface roughness, establishing the foundation for mirror finish.

4

Precision Polishing

Apply ultra-fine diamond compounds (e.g., W1.0, W0.5) to achieve final mirror-grade surface finish. This stage demands exceptional skill and patience.

5

Final Inspection & Verification

• Surface roughness tester: Quantitative measurement of Ra, Rz parameters
• Interferometer: Secondary surface profile verification for shape accuracy
• Visual inspection: Under specific lighting conditions, evaluate reflection integrity by observing potential distortions or defects in mirrored images

Contact Us for More Information

Asahi Optics welcomes your questions, inquires and feedback. Please use the form below or contact us at any of the addresses below.  Our sales team will get back to you shortly.

Sign up for our news

Email: [email protected]
Tel: +86-755-85241681
Fax: +86-755-85241681-0
Wechat: +8618928483413
Skype: asahi-optics
Address: 905 Hengtai Chanye Building, No.1 of TangKeng LuKou Dong , GuanTian, Bao'Shi Dong Road,Shiyan,Bao'an,Shenzhen 518108

© 2010 - 2026 Asahi Optics All rights reserved