Processes

Stereolithography (SLA)

±0.1mm for first 100mm, ±0.1% thereafter

Min Min Wall: 0.5mm; Min Hole: 0.5mm

Selective Laser Sintering (SLS)

±0.3mm or ±0.3%

Min Min Wall: 0.8mm; Min Hole: 1.0mm

Fused Deposition Modeling (FDM)

±0.5mm or ±0.5%

Min Min Wall: 1.2mm; Min Hole: 2.0mm

Multi Jet Fusion (MJF)

±0.2mm or ±0.2%

Min Min Wall: 0.5mm; Min Hole: 0.5mm

Selective Laser Melting (SLM)

±0.1mm - ±0.2mm

Min Min Wall: 0.4mm; Min Hole: 0.6mm

Direct Metal Laser Sintering (DMLS)

±0.1mm for the first 25mm and an additional ±0.002 mm/mm on any additional length.

Min Min Wall Thickness: 0.4 mm

PolyJet Printing

Typically ±0.1mm for features up to 100mm, with an additional ±0.05% for larger dimensions.

Min Min Wall Thickness: 0.6 mm

Digital Light Processing (DLP)

±0.1 mm for the first 100 mm, plus ±0.1% for dimensions beyond that.

Min Min Wall Thickness: 0.2 mm

CNC Milling (3-axis)

Typically ±0.1 mm for the first 25 mm, plus ±0.002 mm for each additional mm. Tighter tolerances are achievable but significantly increase tooling and processing costs.

Min Minimum Draft Angle: 0.5° on highly polished surfaces (SPI-A1/A2); 1-2° is standard for most features; 3°+ for textured surfaces (e.g., VDI 3400).

CNC Milling (4-axis)

Typically +/- 0.100 mm on overmolded features relative to the substrate, but highly dependent on substrate material stability and tooling quality.

Min Min Overmold Wall Thickness: 0.8 mm (for common TPEs)

CNC Milling (5-axis)

Typically ±0.100 mm for plastic features per ISO 2768-m. However, the critical tolerance is the positional accuracy of the insert relative to the plastic features, which can range from ±0.05 mm to ±0.25 mm depending heavily on the mold's locating mechanism.

Min Min Draft Angle: 1.5° to 3° on walls parallel to the mold opening direction. This is critical to prevent ejector pin stress on the plastic-insert interface.

CNC Turning (Lathe)

Typically follows ISO 2768-m. A practical rule is ±0.10 mm for the first 25 mm, plus ±0.002 mm for each additional mm. Tolerances at the material interface are generally looser, around ±0.20 mm.

Min Min Draft Angle: 1° for rigid substrate (e.g., PC, ABS), 0.5° for soft TPE/TPU overmolds. A conservative 2-3° is highly recommended for textured surfaces to prevent scuffing during ejection.

Turn-Mill Machining

Typically ±0.10mm to ±0.25mm, conforming to ISO 3302-1 Class M2 standards.

Min Min Wall Thickness: 0.25 mm

Grinding

Follows standard injection molding tolerances, typically ISO 2768-m. A general expectation is ±0.15mm for features up to 100mm.

Min Minimum Draft Angle: 1.5° on vertical walls. For textured surfaces, a common rule of thumb is to add 1° of draft for every 0.025mm of texture depth to prevent scuffing the decorated surface during ejection.

Drilling / Tapping

+/- 0.5 mm to +/- 1.5 mm, but can exceed +/- 2.0 mm on large, non-critical dimensions due to thermal shrinkage.

Min Min Draft Angle: 1.5° - 3° per side is standard practice to ensure clean part ejection from the mold.

EDM (Electrical Discharge)

Typically +/- 0.8mm for the first 100mm, plus an additional +/- 0.1mm for each subsequent 100mm of dimension.

Min Min Draft Angle: 1-3 degrees (3-5 degrees strongly recommended for deep draws or textured surfaces).

Wire EDM

Typically ±0.1mm (conforming to ISO 2768-m). Tighter tolerances of ±0.025mm are achievable but require additional finishing passes and inspection, significantly increasing cost.

Min Min Wall Thickness: ~0.8mm; Min Hole Diameter: ~1.0mm. Features smaller than this are highly susceptible to vibration and require specialized micro-machining techniques.

Standard Injection Molding

Typically ISO 2768-m. Tighter tolerances of +/- 0.05 mm are achievable on specific features but will increase machining time and cost.

Min Min Wall Thickness: ~1.0 mm; Min Hole Diameter: ~1.0 mm (highly dependent on material and depth-to-diameter ratio).

Overmolding

Typically ±0.1 mm (ISO 2768-m), can achieve ±0.025 mm or better with precision setups and controlled environments.

Min Min Wall Thickness: ~0.5 mm for Aluminum, ~0.8 mm for Steel. Min Hole Diameter: ~0.5 mm. These are heavily dependent on feature depth and material.

Insert Molding

General tolerance follows ISO 2768-m, typically +/- 0.1 mm. Tighter tolerances of +/- 0.01 mm are achievable with finishing passes and process control at a higher cost.

Min Min Wall Thickness: ~0.8 mm. This is highly dependent on material type and overall part rigidity. Thinner walls risk deformation or vibration during machining.

2K / Two-Shot Molding

Typically ±0.05 mm (conforming to ISO 2768-f), but can achieve ±0.005 mm on critical diameters with optimized processes.

Min Min Wall Thickness: ~0.8 mm; Min Hole Diameter: ~1.0 mm (dependent on material and tool rigidity)

LSR Injection Molding

+/- 0.005 mm (Conforming to ISO 286 Grade IT5-IT6)

Min Min Corner Radius: 0.2 mm (Note: This is difficult to maintain, costly, and requires frequent wheel dressing. R0.5mm or greater is strongly preferred for production.)

IMD (In-Mold Decoration)

Drilled Hole Diameter: +/- 0.1 mm (for diameters < 12mm, ref. ISO 2768-m). Tapped Threads: Per class of fit, typically 6H for standard metric internal threads.

Min Min. Commercial Drill Diameter: ~0.5 mm. Min. Standard Tapped Thread: M1.6.

Blow Molding

±0.025 mm (ISO 2768-f). High-precision setups for mold-making can achieve ±0.005 mm.

Min Min Internal Corner Radius: ~0.05 mm (primarily limited by the wire radius plus the spark overcut in Wire EDM).

Thermoforming / Vacuum Forming

±0.025 mm (Standard), achievable down to ±0.003 mm with multiple skim cuts

Min Min. Internal Corner Radius: 0.15 mm (based on a typical 0.25 mm diameter wire)

Vacuum Casting (Urethane)

±0.3mm for the first 100mm, plus ±0.15mm for each additional 100mm.

Min Min Wall Thickness: 0.75 mm

Die Casting

Typically conforms to ISO 8062-3 Grade DCTG 4 to DCTG 6. A practical expectation is ±0.1mm for the first 25mm, plus ±0.0015mm for each additional mm.

Min Min Draft Angle: 1° (external), 2° (internal). Min Wall Thickness: ~0.5mm for Zinc, ~1.5mm for Aluminum.

Sand Casting

Typically +/- 1.5 mm for the first 150 mm, plus an additional +/- 0.008 mm per mm thereafter. A dedicated machining allowance of 3 mm to 6 mm is standard industry practice and should be added to all critical surfaces.

Min Min Wall Thickness: ~4 mm (Ferrous Metals), ~3 mm (Aluminum/Bronze Alloys). Min Draft Angle: 1.5° - 3° on all surfaces parallel to the pattern draw direction.

Investment Casting

Typically ±0.15mm for the first 25mm, with an additional ±0.005mm per mm thereafter (conforming to ISO 8062-3 Grade DCTG 6-8).

Min Min Wall Thickness: 1.5mm (as low as 0.8mm is possible for non-structural features with specific alloys and gating design).

Forging

±0.8 mm (as-forged for a 100mm feature), can be improved to ±0.1 mm with secondary machining operations.

Min Min Draft Angle: 3° for external features, 5°-7° for internal pockets.

Laser Cutting

Typically +/- 0.1mm for thicknesses up to 3mm, increasing to +/- 0.3mm for thicknesses up to 12mm. For higher precision, refer to ISO 9013 standards.

Min Min Hole Diameter: Should be at least 0.8x the material thickness. The absolute minimum is governed by the focused beam diameter, typically around 0.25mm.

Waterjet Cutting

±0.1 mm, but can open to ±0.3 mm on materials thicker than 50 mm due to jet deflection and taper.

Min Min Hole Diameter: ~1.5 mm; Min Wall Thickness: ~1.0 mm. This is fundamentally limited by the kerf width, which is typically 0.8 mm to 1.2 mm.

Plasma Cutting

+/- 0.5 mm for thicknesses up to 12mm; can degrade to +/- 2.0 mm on thicker plates (> 50 mm)

Min Min Hole Diameter / Wall Thickness: ~1.5x Material Thickness

Bending / Press Brake

Typically conforms to ISO 2768-m for general features, with bend-specific tolerances of ±0.3mm (linear) and ±1° (angular).

Min Min Flange Length: A minimum of 4x the material thickness is required to ensure the die can properly support and form the workpiece without slippage or excessive deformation.

Stamping

Typically +/- 0.1 mm, but can achieve +/- 0.05 mm or tighter with high-precision progressive dies and process control.

Min Min Hole Diameter: ~1.0x Material Thickness; Min Web/Wall Width: ~1.5x Material Thickness. Going below these ratios drastically increases punch breakage risk and tooling wear.

Deep Drawing

±0.25 mm to ±0.8 mm, highly dependent on draw depth, material type, and part diameter. Generally follows looser tolerances than machining.

Min Min Internal Corner Radius: 1x material thickness (T) is the absolute minimum limit, but 4T-6T is the recommended range for robust production to prevent tearing.

NCT Punching

Typically +/- 0.1 mm for positional accuracy (ISO 2768-m).

Min Min Hole Diameter >= 1.0x Material Thickness (t). Punching a hole smaller than the material's thickness subjects the punch to extreme column loading, risking tool chipping, buckling, or catastrophic failure.

Aluminum Extrusion

For cross-section: ±0.25 mm on dimensions <25mm; ±1.5% for larger dimensions. For straightness: 1.5 mm per meter. (Based on general commercial standards equivalent to EN 755-9 T2).

Min Min Wall Thickness: 1.2 mm for standard production. As low as 0.8 mm is achievable for small profiles with advanced die design, but this incurs a significant cost premium and process sensitivity.

Plastic Extrusion

Typically falls within ±0.2 mm to ±0.5 mm, but it is highly dependent on the cross-sectional complexity and material thermal stability. Tighter tolerances are achievable with dedicated downstream sizing/calibration tooling.

Min Min Wall Thickness: ~0.75 mm for rigid profiles. Can be significantly lower for flexible tubing or film applications.

Rotational Molding

Typically ±1.5% of the nominal dimension, with a minimum floor tolerance of ±1.5 mm.

Min Min Draft Angle: 1 degree per side for smooth finish; 3-5 degrees for textured surfaces.

Silicone Compression Molding

Typically +/- 0.25mm on dimensions up to 25mm, with tolerance increasing for larger features (approximates ISO 3302-1 Class M2).

Min Min Draft Angle: 0.5° (though 0° is often achievable on shallow features due to material flexibility). Min Wall Thickness: 0.8mm.

Anodizing (Type II)

Typically adds 0.005mm to 0.0125mm of growth per surface. This process adds approximately ±0.01mm to the final part dimensional tolerance stack-up.

Min Coating Thickness: 0.005mm - 0.025mm

Hard Anodizing (Type III)

Adds dimensional growth of approx. 50% of the coating thickness per surface. For a 0.050 mm coating, expect a dimensional change of ~0.025 mm, typically controlled to +/- 0.012 mm.

Min Coating Thickness: 0.025 - 0.075 mm (Typical 0.050 mm; coatings >0.100 mm have a high risk of spontaneous crazing and reduced fatigue life of the substrate).

Powder Coating

This is not a dimensionally precise process. The coating adds thickness, and designers must account for a typical thickness variation of +/- 0.025 mm on top of the part's base tolerance.

Min Coating Thickness: 0.05 - 0.125 mm for standard decorative and protective applications. Can range from 0.025 mm for thin films to over 0.25 mm for heavy functional coatings.

Wet Painting

Typically refers to the coating thickness variation, which is controllable to ±0.015 mm in a well-maintained process.

Min Coating Thickness: 0.02 - 0.12 mm (can be built up in multiple layers for higher thickness)

Electroplating

Typically adds ±0.005 mm to ±0.025 mm to the final part dimension, depending on the specified thickness and part geometry. Precision control is challenging.

Min Coating Thickness: Typically 0.005 mm (5 µm) to 0.025 mm (25 µm) for common zinc or nickel. Can range from 0.0005 mm (decorative chrome) to over 0.25 mm (hard chrome).

Bead Blasting

N/A - This is a non-precision process. Expect dimensional changes of 0.005 mm to 0.025 mm. It should not be applied to surfaces with tolerances tighter than +/- 0.1 mm unless a dimensional offset is planned in the pre-machining stage.

Min Resulting Surface Finish (Ra): Typically 0.8 µm to 3.2 µm. The process will erode/radius sharp external corners to a minimum of ~0.1 mm.

Polishing

±0.025 mm (Note: Polishing is not a primary dimensioning process. It removes material, typically 0.01-0.05 mm, and can degrade the part's original tolerance profile.)

Min Achievable Surface Roughness (Ra): 0.1 μm - 0.4 μm for a standard mechanical polish; < 0.05 μm is achievable for a true mirror finish.

Brushing

This is a cosmetic process with minimal impact on dimensional tolerance (typically < 0.01 mm material removal). It primarily controls surface roughness, typically achieving an Ra of 0.4 to 1.6 µm.

Min Surface Texture Depth: Typically 0.005 mm to 0.025 mm (5 to 25 µm), which is the depth of the grooves created on the surface.

Passivation

Negligible dimensional change; does not typically affect part tolerance as material removal is on the nanometer scale.

Min Passive Layer Thickness: 1-5 nm

Black Oxide

No significant dimensional change; this is a conversion coating, not a plating process. It does not typically require tolerance adjustments.

Min Coating Thickness: 0.0005 - 0.002 mm (0.5 - 2.0 microns)

Electrophoresis (E-Coating)

Does not adhere to general mechanical standards like ISO 2768. The process adds a uniform film; dimensional change must be accounted for in the part design. The coating thickness itself is typically held to a tolerance of ±0.005 mm.

Min Coating Thickness: 0.015 - 0.035 mm

Laser Engraving

Positional Accuracy: +/- 0.1 mm (relative to part datums)

Min Resolution (Min. Line Width): 0.05 mm - 0.2 mm

Film Laminating

+/- 0.5 mm for automated placement accuracy of a die-cut film relative to a part feature.

Min Film Thickness: 0.05 mm - 0.25 mm (common range for protective films, excluding adhesive thickness).

Hydro Dipping / Water Transfer

N/A for geometric tolerances; process adds a surface coating, not intended for dimensional modification.

Min Total Coating Thickness: 0.05 - 0.12 mm (includes base coat, ink layer, and protective clear coat)

Industrial Design (ID)

N/A (Design Process). Designs must be robust for downstream processes, typically accommodating general tolerances of ISO 2768-m for non-critical dimensions.

Min Constraint-driven by the target manufacturing process. Designers must adhere to DFM guidelines (e.g., Min. Wall Thickness for Injection Molding: ~1.5mm for ABS; Min. Draft Angle: 1-2 degrees).

Mechanical Design (MD)

Design-specific, but ISO 2768-m is a widely accepted default for general machined features unless function dictates tighter control.

Min This is not intrinsic to design but is a critical constraint from the target manufacturing process. For example: ~0.8mm wall for CNC Machining (metals), ~1.2mm nominal wall for Injection Molding, ~0.4mm for DMLS/SLM 3D Printing.

CAD Modeling & Drafting

N/A (Process is digital). Drawings specify tolerances for manufacturing. A common baseline for non-critical dimensions is ISO 2768-m, but this is a specification, not an inherent process capability.

Min N/A (Process is digital). The model must conform to the minimum feature size of the intended downstream manufacturing process (e.g., 0.5mm wall for CNC, 1.0mm for injection molding). This is a critical DFM consideration.

CMF Design

Not applicable for dimensional tolerances. For appearance control: Color Match (Delta E < 1.5), Gloss Level (±10% of target GU value).

Min Texture Detail Resolution: This is dependent on the mold texturing method. Chemical Etching can resolve features down to ~0.05 mm, while 5-axis Laser Texturing can achieve micro-features as small as ~0.01 mm.

Design for Mfg (DFM)

Not applicable. DFM is a methodology. The achievable tolerance is entirely dependent on the selected manufacturing process (e.g., ISO 2768-m for general machining, DIN 16742 for plastic injection molding).

Min Not applicable. This is a result of DFM, not a variable. It's entirely dependent on the selected process (e.g., ~0.8mm wall for Injection Molding, ~0.5mm rib for CNC, or 1.5x material thickness for a sheet metal hole diameter).

Cost Estimation

This is an input, not an output. Cost-effective baseline assumption is typically ISO 2768-m for general machined features.

Min This is a key cost driver. Features under 1.0mm (e.g., internal radii, slot widths) often require micro-machining techniques, which exponentially increase cycle time and tool breakage risk, thus driving up cost significantly.