Custom Vacuum Casting Electrical Enclosures with M3 Inserts

Finished ABS-Like PU Housing Sets for Electrical Products

A custom electrical enclosure is more than two plastic covers. The upper and lower housings must align correctly, fastening points need to work together, and the exterior finish must remain consistent after assembly and handling.

For this project, the customer required approximately 20 sets of custom electrical product enclosures for export. Each enclosure consisted of an upper and lower housing, with an overall size of approximately 100 × 40 mm.

The parts were manufactured using vacuum casting with ABS-like polyurethane (PU). M3 threaded inserts were installed at the required fastening locations, and each upper and lower cover was checked as a matched set.

After fit verification, the housings went through detailed surface preparation, including deflashing, deburring, sanding and sandblasting. A matte black two-component (2K) paint was then applied to provide a clean appearance with improved scratch resistance.

The project was delivered as finished enclosure sets ready for the customer's next assembly stage.

Project Details

A Two-Piece Enclosure Must Work as One Product

The upper and lower covers were manufactured as separate components, but they could not be treated as unrelated parts.

Their mating edges, locating features and fastening points had to work together.

After initial trimming, the covers were paired to evaluate:

• Gap consistency
• Edge alignment
• Locating features
• Screw-hole positions
• Local interference
• Opening and closing of the enclosure

Any necessary refinement was completed before cosmetic finishing.

This manufacturing sequence matters because correcting fit after painting can damage the coating and create unnecessary rework.

For this project, assembly compatibility was therefore built into the manufacturing workflow rather than being left for the customer to discover after delivery.

M3 Threaded Inserts Integrated into the Housing

The customer required M3 metal threaded inserts for fastening the enclosure.

Compared with repeatedly fastening screws directly into a cast polymer feature, metal inserts provide a more reliable threaded connection when the housing needs to be assembled and opened during evaluation or product integration.

Insert installation was controlled for position, depth and alignment. The corresponding upper and lower components were then checked together to confirm that the fastening locations matched correctly.

This is a small manufacturing detail, but it has a direct impact on whether the enclosure can be used successfully after delivery.

ABS-Like PU for Custom Enclosure Parts

The customer specified an ABS-like material, so an ABS-like polyurethane (PU) casting resin was used.

This type of material is suitable for vacuum casting applications requiring rigid plastic housings with good detail reproduction and compatibility with secondary finishing.

For this project, it provided the characteristics needed for the enclosure while allowing subsequent sanding, sandblasting and painting.

ABS-like PU is a simulated material rather than actual injection-molded ABS. Where final production parts require specific ABS grades, certifications or production-level material performance, the manufacturing route should be selected accordingly.

Surface Preparation Before Cosmetic Finishing

For this project, the finishing process was particularly important.

Freshly demolded vacuum casting parts can contain parting-line flash, gate remnants and minor surface imperfections. These cannot simply be covered with paint.

The housings therefore went through a controlled preparation sequence:

Deflashing → Deburring → Sanding → Fit Check → Sandblasting → Cleaning

Edges and openings were cleaned carefully, while visible surfaces were refined before sandblasting.

Sandblasting helped create a more uniform surface condition and prepared the housings for the final matte coating.

The objective was not excessive cosmetic processing. It was to establish a clean and consistent base for the required finish.

Why Use a 2K Scratch-Resistant Coating?

Electrical enclosures are handled repeatedly during assembly, testing, packing and installation.

For that reason, the customer specified more than a standard cosmetic black paint.

A two-component (2K) matte black coating was applied to provide improved surface hardness and scratch resistance while maintaining the required low-gloss appearance.

This was particularly important around areas that may be touched during assembly or when the enclosure is opened and closed.

The coating requirement therefore had both an appearance and handling-performance purpose.

From Cast Components to Finished Enclosure Sets

The complete project involved several manufacturing stages:

Vacuum Casting

→ Deflashing & Deburring

→ M3 Insert Installation

→ Upper/Lower Cover Pairing

→ Fit Adjustment

→ Sanding & Sandblasting

→ 2K Matte Black Painting

→ Final Set Inspection

This sequence represents the main value of the project.

The customer did not need to receive cast parts and then coordinate another supplier for inserts, another for painting, and another for assembly checking.

Instead, the enclosure components were processed as complete matched sets before shipment.

Low-Volume Electrical Enclosure Manufacturing

For electrical product developers requiring a limited number of custom housings, vacuum casting can support more than basic part reproduction.

This project combined:

ABS-Like PU Parts + M3 Inserts + Matched Covers + Surface Preparation + 2K Coating + Final Set Inspection

The result was approximately 20 finished electrical enclosure sets prepared for export and subsequent product assembly.

YS Precision supports vacuum casting and urethane casting services for custom plastic housings, covers and structural components, including secondary operations such as threaded inserts, fitting, deburring, surface preparation and painting.

Send us your 3D CAD files, required quantity, material, insert specifications, assembly requirements and surface finish for project evaluation.