Electronics and electrical industries use sheet metal enclosures to enclose PCB, electronics, and electrical components. Sheet metal enclosures have the advantage of low manufacturing costs and turnaround time. This article covers sheet metal enclosure design and the development process for PCB, electrical, and electronics products.
How to Design a Sheet Metal Enclosure
You need to follow the following steps to design a sheet metal enclosure for PCB, electrical, and electronics product. It will ensure the product design is as per customer requirements.
Step-1 : Understand Product design Requirements
The first step in sheet metal enclosure design for a PCB is to understand product functional and aesthetic requirements. These requirements will define enclosure specifications and acceptance criteria.
A Product requirements can include the following points.
- Sheet metal enclosure application.
- Mounting Requirements: Tabletop, wall-mounting, Pole mounting, or 19″ rack mounting.
- Enclosure Working Conditions: Minimum and maximum working temperature, corrosion resistance, IP Rating, vibration resistance requirements, etc.
- Size constraints.
- Aesthetic requirements.
- Part details that you want to enclose inside the sheet metal enclosure. Such as PCB size, component height, and connector positions.
- Connectors or switches to be exposed to a user.
Step-2: Sheet Metal Enclosure Preliminary Design
After we finalize the enclosure design requirements, the next step is to start work on the enclosure’s preliminary mechanical design.
- Enclosure aesthetics design.
- Assembly architecture design.
PCB Enclosure industrial Design
During the industrial design phase, engineers finalize the product aesthetics (form factor, finish, and connector positions). It is an important aspect of product design because product aesthetics impacts product sales.
Designers create various design options to finalize the best product design. PCB Enclosure aesthetics or industrial design impacts the following parameters.
- PCB layout
- Product internal component placement.
- Manufacturing process
- Assembly process.
Therefore it is always recommended to finalize product aesthetics before detailed design. In actual practice, enclosure design and aesthetic design go in parallel.
Critical Points to be considered During Sheet Metal Enclosure Aesthetic Design
You should consider the following points before finalizing PCB enclosure industrial design.
- PCB Layout.
- Interface connectors Position..
- Heat Dissipation Requirements.
- Functional and Performance Requirements.
- Mounting Requirements
- Assembly Process
- Manufacturing Process
- Cost Constraints
Electronics Enclosure Assembly Architecture Design
Engineers consider all design and manufacturing interfaces and customer requirements during enclosure architecture design. Following are the outcomes of enclosure architecture design.
- Product top-level BOM: A class components, fasteners, etc.
- Assembly and disassembly process.
- Design and development risks with a mitigation plan.
- Manufacturing process etc.
Step-3 : PCB Enclosure Detailed Design and Development
Sheet metal enclosure detailed design and development process involves the following tasks:
- Material selection
- Fastener selection
- CAD modeling
- Finish operations
- Assembly operations
Material Selection for Sheet Metal Enclosure Design
Part Material selection ensures product quality and reliability. The following factors affect the selection of the type of material.
- Material Strength: Stainless steel and CRCA have high strength compared to aluminum which is a relatively softer material.
- Corrosion Resistance: If the enclosure has applications in coastal areas or a highly corrosive environment. Experts recommend using highly corrosion-resistant materials such as stainless steel, GI, or Aluminum.
- Electronics Enclosure Weight Constraints: Aluminum has approximately 70% less weight compared to steel or GI.
- Assembly Process: Steel is easy to weld compared to aluminum. Therefore better to go with steel instead of copper or aluminum if the design requires welding.
- Cost: Lower material cost results in low product cost. That means more satisfied customers. This factor needs to be taken seriously at the design stage.
- Thermal and Electrical Conductivity: Copper and aluminum electrical and thermal conductivity are very high. Therefore copper and aluminum materials are a good choice if the design requires a high heat dissipation rate.
Detailed Sheet Metal Enclosure Design (CAD Modeling)
During detailed PCB enclosure design following activities are performed on cad software.
- PCB Mounting Arrangement: We can use PEM Fasteners (Studs, standoff), metal/plastic brackets, and spacers to mount PCBs with an electronics enclosure.
- Cutout for Connectors and User Interfaces: Optimum clearance between PCB connectors and sheet metal cutout ensures smooth product assembly. It is advisable to perform a tolerance stack-up analysis to ensure minimum rejection.
- Cutout for Ventilation and Heat Dissipation: Heat dissipation is becoming very challenging due to the miniaturization of electronics products. Ventilation holes in the enclosure ensure proper heat dissipation. Simulation studies help in manufacturing the first time right product.
- Enclosure joining Operations and Assembly Fasteners: Various sheet metal joining options such as PEM clinching fasteners, welding fasteners, riveting nut, studs, and standoff are available to assemble PCB with enclosure.
- Design verification for assembly and manufacturing: The manufacturing team should review the product design considering part manufacturing and assembly. They should verify features for lean manufacturing and Poka-Yoke etc.
Define Finish Operations
Product final finish operation affects sheet metal enclosure aesthetics and corrosion resistance. The following points are considered during the final finish selection.
- Sheet Metal Material
- Required Corrosion Resistance
- Product aesthetics requirements
- Conductivity requirements
Following is the list of commonly used finish operations on sheet metal parts.
- Powder Coating: Powder coating is applied electrostatically and cured under heat to flow the powder and form skin. Powder coating has application in coating metal parts.
- Chromate Conversion Coating: It is a type of conversion coating used to passivate zinc-plated Steel, aluminum, copper, silver, magnesium, and tin alloys.
- Anodizing: It is an electrolytic process for producing thick oxide coatings on aluminum & its alloys, magnesium, and titanium materials. Anodizing improves surface resistance to wear & corrosion. It adds a decorative layer to the material.
- Zinc Plating
- Nickel plating
- Tin Plating
Step-4 : Prototype Development and Verification
Prototyping
After finalizing product design, the next step is sheet metal prototyping. Prototyping ensures the designed part will meet required expectations. Prototyping part cost is high compared to production parts.
Verification
Prototype parts are verified and tested as per product functional, aesthetics, and assembly requirements.
Step-5: Product Validation Testing
A product requires Validation testing as per its functional requirements. The validation team can do these tests on prototypes if production and prototyping parts are similar.
Product Validation Tests
Following are the major mechanical tests done on sheet metal enclosures but not limited to this list.
- Salt Spray Test
- Scratch Test
- Drop Test
- High-temperature test
- Low-temperature test
- Temperature cycling test
- Wire Pull Test
- Ingress Protection Test
Step-6: Production Ramp-up and Product Launch
After successful prototype development, verification and validation. Team release the product for final production with a quality plan, Testing jigs, and fixtures.
To sum up, Sheet metal enclosures has the advantage of low manufacturing cost and low turnaround time. Manufacturers can deliver sheet metal parts within one week’s time.
We will keep updating this article on sheet metal enclosure design for electronics products. If you need any support in sheet metal enclosure design. Please add your comments or questions in the comment box.
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