FAQ

Frequently Asked Questions About Custom Metal Enclosures

Material Selection

1. What are the performance differences between stainless steel, aluminum alloy, galvanized steel sheet, and cold-rolled steel sheet?

Acier inoxydable:
Stainless steel offers excellent corrosion resistance and strong resistance to acids, alkalis, salt spray, and humid environments. It is suitable for harsh outdoor conditions and demanding industrial environments. The service life can exceed 10 years.

Aluminum Alloy:
The key advantages of aluminum alloy are lightweight properties and superior thermal conductivity. Its density is approximately one-third that of steel, and its thermal conductivity is about five times higher than steel. It is ideal for enclosures used in energy storage systems, inverters, and other heat-generating electronic equipment.

Galvanized Steel Sheet:
Galvanized steel sheet is protected by a zinc coating that provides electrochemical (sacrificial anode) protection. Its corrosion resistance is superior to ordinary carbon steel and is suitable for humid and salt-spray environments, with a service life of 15–20 years.

Cold-Rolled Steel Sheet:
Cold-rolled steel provides relatively high yield strength and good ductility at a competitive cost. It is one of the mainstream material choices for industrial cabinets and electrical enclosures.

2. How should material selection be determined based on the operating environment?

Material selection for custom metal enclosures should primarily be based on the operating environment:

For outdoor or high-humidity environments, 304 or 316 stainless steel or galvanized steel with a zinc coating thickness ≥ 8 μm is recommended.
For lightweight requirements (such as telecom cabinets), 5-series aluminum alloys (5052/5083) are preferred, as their density is approximately 60% lighter than carbon steel.
For high-temperature environments, materials with good thermal stability must be considered.
For PLC control cabinets used in workshops where oil contamination and mechanical vibration are common, powder-coated cold-rolled steel enclosures provide excellent impact resistance, easy cleaning, and optimal cost performance.
For coastal or marine environments (par ex., tidal monitoring equipment), ordinary carbon steel may corrode within six months due to salt spray exposure. In such cases, aluminum alloy or 316 stainless steel is mandatory.

3. What are the cost differences among various materials?

Material cost is a critical factor in enclosure fabrication. Based on market pricing, the general ranking of material cost (from high to low) is:

Titanium alloy > Stainless steel (316 > 304) > Aluminum alloy > Galvanized steel > Cold-rolled steel.

Approximate material prices:

Stainless steel: ~ RMB 14,500 per ton
Aluminum alloy: ~ RMB 13,000 per ton
Galvanized steel: ~ RMB 5,000 per ton

In terms of machining costs:

Aluminum alloy (par ex., 6061: RMB 20–30/kg; 7075: RMB 50–80/kg) generally has lower machining cost.
Stainless steel (304: RMB 50–80/kg; 316: RMB 80–120/kg) has the highest machining cost.

Overall, stainless steel material cost can be 2–4 times that of aluminum alloy.

4. What advantages do metal enclosures have compared to plastic enclosures?

Metal enclosures offer significantly higher mechanical strength, rigidity, and impact resistance, providing superior protection for internal precision electronic components. Plastic enclosures are more prone to cracking, deformation, and wear in industrial environments.

In addition:

Metal materials are non-combustible and inherently fire-resistant.
Plastic materials may degrade, corrode, soften, or become brittle in environments involving oil, solvents, dust, or humidity.
In terms of thermal management, aluminum alloy has far superior thermal conductivity compared to plastic and acts as a natural heat sink, efficiently dissipating heat from internal chips and components.

Manufacturing Process-Related Questions

We primarily use CNC machining and sheet metal fabrication for custom metal enclosures, offering high precision and meeting the majority of market demands. Common fabrication processes include CNC machining, sheet metal forming, die casting, and aluminum extrusion. Different manufacturing processes directly affect dimensional accuracy, production cost, and lead time.

1. What are the main manufacturing processes for custom metal enclosures and their characteristics?

CNC Machining:
High precision with tolerances up to ±0.01 mm. Suitable for small-batch and high-precision products. Higher unit cost per part.

Sheet Metal Fabrication:
Suitable for large-sized enclosures. High efficiency and lower cost. Limited capability for complex curved surfaces.

Die Casting:
Suitable for high-volume production of complex geometries. Low unit price but high tooling (mold) cost.

Aluminum Extrusion:
Suitable for long-profile products with 2D cross-sectional stretching. Relatively lower tooling cost compared to die casting.

2. How should the appropriate manufacturing process be selected?

Process selection should consider unit cost, tooling investment, and economic production volume.

Unit cost ranking (low to high): Die casting < Sheet metal < Extrusion < CNC
Tooling cost ranking (low to high): CNC (almost zero) < Sheet metal (very low) < Extrusion (medium-low) < Die casting (very high)
Economic production volume:
- CNC: 1–500 units
- Sheet metal: 1–2,000 units
- Extrusion: 500–10,000 units
- Die casting: 5,000+ units

For example: When order quantity exceeds 5,000 units, die casting is typically the most economical solution. – For prototyping or small-batch production, CNC machining is preferred. – For enclosures requiring large internal space, sheet metal fabrication offers the best cost-performance ratio.

3. What are the precision grades of different processes?

CNC machining: ISO 2768-f (fine tolerance), ±0.01–0.05 mm
Die casting and aluminum extrusion: ISO 2768-m (medium tolerance)
Sheet metal forming: ISO 2768-c (coarse tolerance)

4. What design considerations apply to different fabrication processes?

CNC Machining:
Minimum internal corner radius ≥ R1.0 mm. Avoid deep holes or cavities exceeding 10 times the tool diameter.

Sheet Metal Fabrication:
Consider bend allowance (K-factor) and proper design of PEM nuts/studs.

Die Casting:
Include proper draft angles, parting line design, and address porosity concerns.

Aluminum Extrusion:
Optimize cross-sectional cantilever ratios and avoid excessively deep or narrow open slots.

Dimensional Accuracy

Dimensional accuracy directly impacts assembly and functional performance.

1. What machining tolerances can be achieved?

Standard CNC machining: ±0.1 mm
Precision machining: ±0.01 mm or better

Example cases: – 6061-T6 enclosure tolerance: ±0.008 mm – AZ91D bracket hole deviation ≤ 0.005 mm – H62 connector insertion interface tolerance: ±0.006 mm

2. How do accuracy requirements vary by industry?

General industrial products: deviation beyond ±0.3 mm is considered non-conforming.
Precision electronics and medical applications: ≤ ±0.2 mm.
Power control cabinets: dimensional tolerance ≤ ±0.05 mm; geometric tolerance ≤ ±0.02 mm/m.
Injection molding critical dimensions: CPK ≥ 1.67 (industry benchmark ≥ 1.33), assembly first-pass yield > 99%.

3. How is dimensional consistency ensured in mass production?

We implement:

Temperature-controlled machining environments
Thermal compensation technology
Automatic tool setting systems
Tool wear compensation functions

Without these measures, dimensional deviation may occur after extended production runs.

4. Surface roughness requirements

General industrial products: Ra ≤ 1.6 μm
Precision products: Ra ≤ 0.8 μm
Standard punching: Ra 12.5–25 μm
Precision blanking: Ra 0.8–3.2 μm

For appearance surfaces: – No visible scratches or defects at 50 cm viewing distance – Color consistency controlled by colorimeter (ΔE < 2.0)

Surface Treatment

Surface finishing affects not only aesthetics but also corrosion resistance and service life.

1. What surface treatment processes are available?

Powder coating
Electroplating (nickel plating for corrosion resistance, chrome plating for wear resistance)
Anodisation (primarily for aluminum alloys; oxide film thickness 5–25 μm)
Electrophoretic coating (e-coating)

2. How to select appropriate surface treatment?

Aluminum enclosures: anodizing; sandblasting/brushing + anodizing for improved appearance and durability
Carbon steel: powder coating or galvanizing
Outdoor use: enhanced anti-corrosion treatment
EMI shielding: conductive coatings or metallic plating

Examples: – Industrial equipment: thick anodizing for durability and corrosion resistance – Consumer electronics: 6063 aluminium + fine sandblasting + anodizing for premium appearance and texture

3. Impact of surface treatment on performance

Electrostatic powder coating thickness: 70–90 μm; curing temperature: 180–200°C
Hard anodizing: thicker oxide layer, hardness ≥ 300HV
Galvanizing: salt spray resistance 1,000–1,500 hours

4. How is surface treatment quality controlled?

Key controls include pre-treatment (cleaning, degreasing) and strict parameter monitoring.

Example parameters: – Anodizing sulfuric acid concentration: 15–20% – Temperature: 18–22°C – Oxide film thickness: 10–15 μm – Powder coating thickness: 50–80 μm – Adhesion: ≥ 4.5 MPa – Salt spray resistance: ≥ 48 heures – Plating thickness: 5–25 μm – Cross-cut adhesion test: ≥ 4B – Copper sulfate spot test: > 30 seconds

Production Lead Time

1. What is the lead time for standard enclosures?

Standard production lead time: 15–25 days.

2. What is the lead time for custom products?

Standard custom enclosure: 15–25 days after sample approval and deposit
Urgent orders: 7–15 days
Complex tooling: 45–60 days from mold design to pilot production

Product development stages: Quotation → Tooling → Hardware validation → Engineering validation → Design validation → Production validation → Mass production ramp-up

Full project development cycle: approximately 6–8 months.

3. Factors affecting lead time

Design complexity
Order quantity
Process selection (tooling requirement)
Raw material supply
Surface finishing requirements

4. How to shorten lead time?

We adopt a “three-stage parallel production model”:

Parameter pre-review
Modular selection
Process optimization

This can reduce a 15-day delivery schedule to approximately 10 jours.

Production Capacity

Factory size: 139,930 square feet
Monthly capacity: 5,000 units
Two production lines with rapid changeover capability
Suitable for multi-variety, small-to-medium batch production
On-time delivery rate: 99%
Emergency order response within 48 heures

Contrôle de qualité

We strictly implement the ISO 9001 Quality Management System.

1. Quality control system

Three-level inspection:

QI (Incoming Quality Control)
IPQC (Contrôle qualité en cours de processus) – includes patrol inspection and first article inspection
OQC (Outgoing Quality Control)

Mass production begins only after first article approval.

2. Certifications

ISO 9001
CE
RoHS

3. Handling of quality issues

Immediate isolation of non-conforming products
Root cause analysis
Corrective and preventive actions (CAPA)
Implementation and effectiveness verification
Customer notification and resolution (if necessary)
Documentation and archiving

Overall quality pass rate: 99%.

Customization Capability

1. Minimum order quantity (MOQ)

Prototyping supported from 1 unit.

2. Design and R&D process

Requirement confirmation → Industrial design → Structural design → Program design → Prototyping → Sample validation.

3. Sample production process

Customer provides drawings/samples → Evaluation and quotation → Production → Video or physical sample confirmation → Modification (if required) → Mass production.

4. Design services

Structural design
3D modeling and rendering
Design for Manufacturability (DFM) optimization
Material and process selection guidance
Cost analysis and optimization recommendations

Explosion-Proof Enclosures

1. Special requirements

Explosion-proof enclosures must comply with GB3836.1-2010 (General Requirements for Electrical Equipment for Explosive Atmospheres).

Must withstand internal explosion pressure (0.8–1.5 MPa)
No cracking, deformation, or leakage
Material: 304 stainless steel or galvanized carbon steel
Continuous welding or sealant treatment at joints
Minimum protection rating: IP54

2. Material requirements

304 stainless steel or galvanized carbon steel
Non-metal materials must be flame-retardant (oxygen index ≥ 28%)
Aluminum alloy must be anodized
All materials must meet required explosion-proof grade

3. Explosion-proof certification process

Design compliance → Accredited certification body selection → Document submission → Type testing → Factory audit → Certification issuance → Annual surveillance audit.

4. Usage precautions

Do not disassemble in hazardous areas
Regular inspection of sealing surfaces
Ensure proper grounding
Use certified explosion-proof accessories
Operate only in designated hazardous zones
Establish periodic maintenance system

EMI Shielding Enclosures

1. Function

Prevent electromagnetic interference (EMI) and radio frequency interference (RFI), ensuring normal operation of internal electronics and preventing signal leakage.

2. Material selection

High conductivity materials (copper, aluminium)
Increased thickness improves shielding effectiveness
Stainless steel provides corrosion resistance with good shielding
Consider cost and manufacturability
For high-frequency shielding, conductivity is more critical than thickness

3. Shielding effectiveness testing

Shielded chamber testing across frequencies
Magnetic field shielding test
Electric field shielding test
Plane wave shielding test
Standards: MIL-STD-461, FCC Part 15

4. Design considerations

Conductive treatment at seams (soudage, conductive gaskets)
Aperture size < 1/20 of the highest interference wavelength
Shielded cables or conduits at cable entry points
Proper grounding design
Conductive sealing gaskets
Avoid insulating breaks in shielding continuity

Outdoor Waterproof Enclosures

1. Protection rating requirements

IP65: Dust-tight, protected against water jets
IP66: Dust-tight, protected against powerful water jets
IP67: Dust-tight, temporary immersion (1 m for 30 min)
IP68: Dust-tight, long-term immersion
IP69K: Dust-tight, high-pressure, high-temperature washdown resistant

2. Material and design requirements

316 stainless steel or aluminum alloy
UV-resistant surface treatment (par ex., fluorocarbon coating)
Silicone rubber or EPDM seals
Double-layer structural design
Drainage holes at bottom
Reinforcement ribs
Multi-layer sealing structure

3. Environmental adaptability

Operating temperature: −40°C to +60°C (or wider for extreme regions)
UV resistance
Salt spray resistance for coastal regions
Impact resistance (hail, animals)
Vibration resistance (wind, seismic activity)

4. Installation and maintenance requirements

Avoid water accumulation at installation site
Ensure proper grounding (lightning protection)
Regular inspection of sealing surfaces
Avoid damage during installation
Clean drainage holes periodically
Inspect enclosure integrity and fasteners
Maintain service records for traceability