CCJC OPTICS

Selection of Tooling in Optical Lens Processing

2026-02-05 15:26

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Optical lens processing is a precision-oriented manufacturing process that involves multiple steps such as cutting, grinding, polishing, and grooving. The selection of appropriate tooling directly determines the processing accuracy, surface quality, production efficiency, and cost control of optical lenses. With the increasing demand for high-precision lenses in fields such as photography, optoelectronics, medical equipment, and aerospace, the scientific selection of tooling has become a core link in ensuring product competitiveness. This guide systematically elaborates on the selection principles, key tooling types, and practical selection strategies for optical lens processing, covering common processing links and material characteristics.

1. Core Principles for Tooling Selection in Optical Lens Processing

The selection of tooling in optical lens processing must adhere to the core logic of "matching process requirements, adapting to material properties, balancing precision and efficiency, and controlling comprehensive costs". Specific principles are as follows:

1.1 Matching Processing Precision and Surface Quality Requirements

Optical lenses have strict requirements on surface roughness (Ra), surface shape accuracy, and dimensional tolerance. For example, precision lenses used in cameras and microscopes require surface roughness Ra ≤ 0.005 μm and surface shape accuracy within 0.001 mm, which requires tooling with high wear resistance and stability. In contrast, ordinary optical lenses for daily use have relatively loose requirements, and cost-effective tooling can be selected to balance performance and cost.

1.2 Adapting to Lens Material Characteristics

Optical lenses are mainly divided into glass lenses and plastic (resin) lenses, and their hardness, wear resistance, and chemical stability vary significantly, which directly affects tooling selection. Glass lenses (such as quartz glass, K9 glass, and fluorite glass) have high hardness and brittleness, requiring tooling with high hardness and good impact resistance; plastic lenses have low hardness but good toughness, and tooling with sharp cutting edges and low wear is preferred to avoid material deformation and burrs.

1.3 Balancing Processing Efficiency and Tooling Service Life

High-efficiency tooling can shorten the processing cycle and improve production capacity, but it may lead to reduced service life and increased replacement costs. On the contrary, tooling with long service life may have low processing efficiency, affecting production progress. Therefore, the selection needs to balance the two according to the production volume: high-volume mass production prioritizes efficient and wear-resistant tooling, while small-batch custom processing can focus on tooling stability and service life.

1.4 Considering Cost-Effectiveness and Practical Applicability

High-precision tooling often has a high price, so it is not necessary to pursue high-end tooling blindly. For ordinary processing scenarios, cost-effective tooling that meets the basic requirements can be selected; for special processes (such as ultra-precision polishing and aspherical lens processing), high-performance tooling should be invested in to avoid rework caused by tooling defects, thereby reducing comprehensive costs.

2. Selection of Key Tooling for Major Optical Lens Processing Links

Optical lens processing involves multiple consecutive links, and each link has corresponding core tooling. The selection of tooling should be targeted according to the processing purpose and technical requirements of each link.

2.1 Tooling Selection for Cutting Process

The cutting process is the first step in optical lens processing, mainly used to cut raw materials (such as glass ingots and resin blanks) into rough blanks of the required size and shape. The core requirement for tooling is high cutting accuracy and no damage to the blank surface.

2.1.1 Cutting Tools

Diamond tools are the first choice for optical lens cutting due to their high hardness and wear resistance. Specifically:

Diamond cutting blades: Suitable for cutting glass lenses, especially high-hardness materials such as quartz glass and sapphire. The blade should be selected according to the thickness of the blank and the cutting speed—thick blanks use thick-blade diamond blades with high rigidity to avoid blade deformation, while thin blanks use thin-blade blades to reduce material loss.
Diamond wire saws: Suitable for cutting brittle and delicate lenses (such as fluorite glass lenses) and aspherical lens blanks. The thin diamond wire (diameter 0.1-0.3 mm) can achieve narrow kerf cutting, minimize material waste, and the high-speed movement of the wire ensures smooth cutting surfaces without chipping.

2.1.2 Cutting Equipment

The selection of cutting equipment is closely matched with cutting tools, and it is divided into automatic, semi-automatic, and manual types according to the degree of automation:

Automatic cutting machines: Equipped with integrated software and sensors, they can realize full-automatic measurement, positioning, and cutting, with high cutting accuracy and efficiency. Suitable for high-volume mass production of standard lenses, such as eyewear lenses and ordinary optical windows.
Manual cutting machines: Rely on the operator's skill to control the cutting process, with low equipment cost and strong flexibility. Suitable for small-batch custom processing and sample production, but the cutting accuracy is affected by the operator's proficiency.
CNC cutting machines: Controlled by computer numerical control, they can realize precise cutting of complex shapes (such as non-circular lens blanks) and have high repeatability. Suitable for processing high-precision and complex-shaped lenses, such as camera lenses and medical optical lenses.

2.2 Tooling Selection for Grinding Process

The grinding process is used to remove the surface defects of the cutting blank, correct the shape and size, and lay the foundation for subsequent polishing. The core requirements for tooling are high grinding accuracy, uniform material removal, and no new surface scratches.

2.2.1 Grinding Wheels

Diamond grinding wheels are the core tooling for optical lens grinding, and their selection is mainly based on the lens material, grinding precision, and grinding efficiency:

Metal-bonded diamond grinding wheels: With high rigidity and wear resistance, they are suitable for rough grinding of high-hardness glass lenses (such as quartz glass and borosilicate glass). The grit size is usually 1000#-1200#, which can quickly remove the cutting damage layer and improve grinding efficiency.
Resin-bonded diamond grinding wheels: With good elasticity and self-sharpening, they are suitable for fine grinding of optical lenses. The grit size is 1500#-1800#, which can reduce surface roughness to Ra ≤ 0.10 μm and avoid surface scratches. They are widely used in the fine grinding of camera lenses and precision optical components.
Ceramic-bonded diamond grinding wheels: With high temperature resistance and chemical stability, they are suitable for high-speed grinding of large-diameter optical lenses (such as aerospace lenses). They have the advantages of uniform grinding and long service life, but the cost is relatively high.

2.2.2 Grinding Equipment

Grinding equipment is divided into CNC grinding machines and manual grinding machines according to the degree of automation:

CNC grinding machines: Including CNC lathes, CNC milling machines, and CNC grinding machines, they can realize multi-axis linkage control and precise grinding of complex surfaces (such as aspherical lenses). CNC grinding machines have high grinding accuracy (surface shape accuracy up to 0.001 mm) and good repeatability, which is the mainstream equipment for high-precision lens grinding.
Manual grinding machines: Simple in structure and low in cost, they are suitable for small-batch grinding of ordinary optical lenses. However, the grinding accuracy is affected by the operator's skill, and it is difficult to meet the requirements of high-precision lenses.

2.3 Tooling Selection for Polishing Process

The polishing process is the key link to ensure the surface quality of optical lenses, which is used to remove the grinding marks on the lens surface, improve the surface finish and transparency, and make the surface roughness reach the required index (usually Ra ≤ 0.005 μm). The core tooling for polishing is polishing pads (polishing skins) and polishing fluids, which need to be matched with each other.

2.3.1 Polishing Pads (Polishing Skins)

According to the base material and polishing mechanism, polishing pads are mainly divided into four categories, which are suitable for different polishing scenarios:

Non-woven polishing pads: The most commonly used type, made of polyester/nylon non-woven fabric bonded by hot pressing/resin, with a porous structure that can store polishing fluid. They have moderate elasticity, strong abrasive adsorption, and a balance between polishing efficiency and precision, suitable for the polishing of most ordinary optical glass (such as K9 glass and BK7 glass). They are divided into low-porosity (hard type), medium-porosity (general type), and high-porosity (soft type) according to the porosity.
Polyurethane (PU) polishing pads: Made of microporous polyurethane elastomer, they have excellent elasticity, uniform and dense surface, and no hair loss risk. They can achieve ultra-precision polishing and mirror effect, with surface roughness up to Ra 0.001-0.005 μm, which is the core tooling for ultra-precision polishing of optical lenses. They are divided into rigid foam PU (good shape retention), flexible foam PU (fitting curved surfaces), and hydrophilic PU (suitable for water-based polishing fluids).
Flocked polishing pads: With polyester film/non-woven fabric as the base, and nylon/polyester short fluff planted on the surface (fluff length 0.1-0.5 mm), they have excellent flexibility and fit, suitable for the polishing of curved, aspherical, and special-shaped optical lenses. They can avoid scratching the curved surface and are divided into short fluff (high-precision curved surfaces) and long fluff (large curvature curved surfaces).
Soft abrasive polishing pads: With sponge/rubber as the base, and a soft abrasive layer (such as alumina and cerium oxide) compounded on the surface, they have high polishing efficiency and can quickly remove the grinding damage layer. They are suitable for rough polishing and medium polishing, but not for fine polishing or mirror polishing, as they are prone to produce surface micro-scratches.

2.3.2 Polishing Fluids

Polishing fluid is an auxiliary tooling for polishing, which is used to reduce the friction between the polishing pad and the lens surface, remove the polished debris, and improve the polishing effect. The selection should be matched with the polishing pad and lens material:

Cerium oxide polishing fluid: The most commonly used polishing fluid, with good polishing effect and low cost, suitable for polishing ordinary glass lenses (such as K9 glass and BK7 glass), matching non-woven polishing pads and PU polishing pads.
Silica polishing fluid: With high polishing precision, suitable for ultra-precision polishing of high-hardness glass lenses (such as quartz glass and sapphire), matching rigid foam PU polishing pads.
Alumina polishing fluid: Suitable for rough polishing of glass lenses, with high material removal rate, matching soft abrasive polishing pads.
Neutral polishing fluid: Suitable for polishing low-hardness and corrosion-prone glass lenses (such as flint glass and fluoride glass), avoiding chemical corrosion of the lens surface, matching hydrophilic PU polishing pads and flocked polishing pads.

2.3.3 Polishing Equipment

Polishing equipment is divided into automatic polishing machines and manual polishing machines:

Automatic polishing machines: Including microcomputer-controlled automatic polishing machines and CNC polishing machines, they can realize precise control of polishing pressure, speed, and time, with high polishing accuracy and efficiency. Suitable for high-volume mass production of high-precision lenses, such as camera lenses and medical optical lenses.
Manual polishing machines: Simple in operation and low in cost, suitable for small-batch custom processing and sample polishing. The polishing effect depends on the operator's skill, and it is difficult to ensure the consistency of surface quality.

2.4 Tooling Selection for Grooving Process

The grooving process is mainly used for cutting precise grooves on the lens surface, which is convenient for lens mounting, alignment, and assembly. The core requirements for tooling are high grooving accuracy, uniform groove depth, and smooth groove surface.

2.4.1 Grooving Tools

Diamond grooving tools: With diamond particles embedded on the cutting edge, they have high hardness and wear resistance, suitable for grooving glass lenses and resin lenses. The tool size is selected according to the groove width and depth—narrow grooves use thin-edged tools, and deep grooves use thick-edged tools with high rigidity.
Mean-ball grooving tools: Using spherical ball-shaped cutting tools to engrave smooth and accurate grooves, suitable for high-precision grooving of lenses that need to be integrated with complex frames, such as custom eyewear lenses and precision optical components.

2.4.2 Grooving Equipment

Grooving equipment is divided into the following types according to the processing method and automation degree:

CNC grooving machines: Controlled by computer numerical control, they can realize automatic grooving of complex groove shapes and multi-axis cutting, with high grooving accuracy and repeatability. Suitable for high-volume mass production and complex groove processing, such as industrial lens assembly grooves.
Diamond wire grooving machines: Using diamond wire to cut grooves, with minimal material loss and smooth groove surfaces, suitable for grooving brittle and delicate lenses (such as sapphire lenses) and low-waste production environments.
Single-axis grooving machines: Manually operated, simple in structure and low in cost, suitable for small-batch grooving of ordinary lenses and repair work, but only suitable for straight or simple curved grooves.

3. Key Factors Affecting Tooling Selection

3.1 Lens Material

As the core basis for tooling selection, the hardness, brittleness, and chemical stability of the lens material directly determine the type and performance of tooling. For example, high-hardness glass (quartz glass, borosilicate glass) requires diamond tools with high hardness; low-hardness resin lenses require sharp and wear-resistant tools; corrosion-prone glass (fluoride glass) requires tooling and polishing fluid with good chemical compatibility.

3.2 Processing Precision and Surface Quality Requirements

The higher the processing precision and surface quality requirements, the higher the performance requirements for tooling. For example, ultra-precision polishing requires PU polishing pads and high-purity polishing fluid; aspherical lens grinding requires CNC grinding machines and high-precision diamond grinding wheels. If the precision requirements are low, ordinary tooling can be selected to reduce costs.

3.3 Production Volume and Processing Batch

High-volume mass production prioritizes automatic equipment and efficient, wear-resistant tooling to improve production capacity and reduce unit processing costs; small-batch custom processing can select manual or semi-automatic equipment and flexible tooling to adapt to the diversity of product specifications.

3.4 Processing Cost Budget

Tooling cost accounts for a certain proportion of the total processing cost. High-precision tooling (such as CNC equipment, PU polishing pads) has high prices but can reduce rework rates and improve product quality; cost-effective tooling (such as non-woven polishing pads, manual equipment) has low prices but is suitable for ordinary processing scenarios. The selection needs to balance cost and quality according to the actual budget.

3.5 Operator Skill Level

Automatic equipment (such as CNC grinding machines, automatic polishing machines) requires operators to have professional programming and operation skills; manual equipment has low requirements on operator skills but requires rich experience to ensure processing quality. Therefore, the selection of tooling and equipment should also consider the skill level of the on-site operators to avoid equipment idleness or processing defects caused by improper operation.

4. Practical Selection Strategies and Case Analysis

4.1 Selection Strategy Summary

The selection of tooling in optical lens processing can follow the "three-step" strategy: first, clarify the processing requirements (precision, surface quality, production volume); second, determine the tooling type according to the lens material and processing links; third, balance efficiency, service life, and cost to select specific tooling models and specifications. At the same time, attention should be paid to the matching between tooling and equipment, and between tooling and auxiliary materials (such as polishing fluid), to maximize the processing effect.

4.2 Typical Case Analysis

Case 1: Mass production of K9 glass flat precision lenses (Ra ≤ 0.01 μm). Processing links: cutting → rough grinding → fine grinding → polishing. Tooling selection: Automatic cutting machine + diamond cutting blade; metal-bonded diamond grinding wheel (1200#) for rough grinding; resin-bonded diamond grinding wheel (1500#) for fine grinding; medium-porosity non-woven polishing pad + cerium oxide polishing fluid for polishing. This combination balances efficiency and precision, with low comprehensive cost, suitable for mass production.
Case 2: Small-batch custom processing of quartz glass aspherical lenses (Ra ≤ 0.005 μm). Processing links: cutting → CNC grinding → ultra-precision polishing. Tooling selection: CNC cutting machine + diamond wire saw; CNC grinding machine + resin-bonded diamond grinding wheel (1800#); rigid foam PU polishing pad + high-purity silica polishing fluid. This combination ensures high grinding and polishing precision, adapting to the complex shape of aspherical lenses and small-batch custom needs.
Case 3: Mass production of resin eyewear lenses. Processing links: cutting → grinding → grooving → polishing. Tooling selection: Semi-automatic cutting machine + diamond cutting blade; resin-bonded diamond grinding wheel (1000#); CNC grooving machine + diamond grooving tool; non-woven polishing pad + cerium oxide polishing fluid. This combination has moderate precision and high efficiency, meeting the cost requirements of mass production of eyewear lenses.

5. Tooling Use and Maintenance Tips

The correct use and maintenance of tooling can extend its service life, ensure stable processing quality, and reduce replacement costs. Key tips are as follows:

Preprocessing: New polishing pads should be soaked in pure water for 10-20 minutes before use to squeeze out internal air bubbles and ensure uniform adsorption of polishing fluid; diamond tools should be inspected for edge damage before use, and replaced in time if there are cracks or wear.
Parameter control: During processing, the cutting speed, grinding pressure, polishing speed, and other parameters should be adjusted according to the tooling type and lens material to avoid tooling damage and processing defects caused by excessive parameters.
Cleaning and maintenance: After processing, the tooling should be cleaned in time—polishing pads should be cleaned with pure water to remove residual abrasive and debris, and dried before storage; diamond grinding wheels and cutting tools should be cleaned to remove debris and avoid blockage.
Storage environment: Tooling should be stored in a dry, clean, and dust-free environment. Polishing pads should be avoided from moisture and mildew; diamond tools should be avoided from collision and corrosion to prevent edge damage.
Replacement timing: When the tooling shows obvious wear (such as polishing pad fluffing, diamond tool edge blunting), or the processing quality deteriorates (such as lens surface scratches, dimensional deviation), the tooling should be replaced in time to avoid affecting the product quality.

6. Conclusion

The selection of tooling in optical lens processing is a systematic project that involves multiple factors such as processing links, lens materials, precision requirements, production volume, and cost budget. It is necessary to adhere to the core principles of matching, adaptation, balance, and cost-effectiveness, select targeted tooling for each processing link, and pay attention to the matching between tooling, equipment, and auxiliary materials. At the same time, through correct use and scientific maintenance, the service life of tooling is extended, the stability of processing quality is ensured, and the comprehensive competitiveness of optical lens products is improved.

With the continuous development of optical processing technology, new types of tooling (such as nano-diamond polishing pads and high-precision CNC equipment) are constantly emerging. It is necessary to keep abreast of the latest technical trends, update tooling selection concepts, and adapt to the increasing demand for high-precision and high-efficiency optical lens processing.