A TWS charging case is one of the first parts users see and touch. Its gloss, opening edge, lid gap, curved reflection, and hand feel all affect the quality of the final product.
Yishun Optical makes custom mirror mold cores and inserts for Bluetooth earphone charging cases. We support outer shells, upper lids, lower housings, opening areas, deep inner cavities, trays, decorative surfaces, multi-cavity inserts, and replacement mold components.
For charging case molds, making the surface bright is only one part of the work. The opening shape, edge sharpness, curved surface, parting line, cavity consistency, and long-term molding stability are just as important.
Developing a New TWS Charging Case?
Send us your drawing, material, mirror finish target, cavity quantity, and any current molding problem. We will first review the opening edge, deep cavity, high-gloss surface, and areas that may be difficult to polish.
Product Description
Main Use
This type of mold is mainly used for injection molding high-gloss TWS charging case parts. Common products include the outer charging case shell, upper lid, lower case, internal tray, opening area, decorative panel, glossy black part, transparent window, and other visible consumer electronic parts.
A stable mirror mold surface can reduce later sanding, painting, and surface correction for suitable plastic parts. It can also help the molded case achieve a cleaner reflection and a more consistent appearance before coating or assembly.
What Makes Charging Case Molds Difficult
A charging case usually has broad curved surfaces and a clear opening. These areas reflect light strongly, so even a small wave mark, dull area, scratch, or local shape change can be easy to see.
The opening edge is another key area. If it is polished too much, the edge may become rounded and the lid gap may look different after assembly. Deep inner curves and narrow corners can also be hard to reach, which makes the polishing result less stable.
Typical Machining and Mirror Polishing Process
We begin with a drawing review. We identify the main appearance surface, opening edge, parting line, deep cavity, R corners, thin-wall areas, fitting surfaces, and any cavity-to-cavity requirements.
We use 5-axis CNC precision machining to form the main curve and cavity geometry. Depending on the drawing, the process may also include grinding, precision finishing, mirror machining, controlled manual polishing, or automated polishing.
The polishing path and removal amount are controlled around opening edges, R corners, deep curves, and small steps. The goal is to improve mirror quality without changing the charging case shape or weakening the edge.
Technical Reference
| Item | Typical Requirement / Capability |
|---|---|
| Suitable products | TWS charging case outer shells, upper lids, lower housings, inner trays, opening areas, decorative panels, transparent windows, multi-cavity inserts, and replacement mold cores |
| Common materials | PC/ABS, transparent PC, translucent materials, high-gloss black plastics, parts before coating or electroplating, and other confirmed molding materials |
| Main process | 5-axis CNC precision machining, mirror machining, grinding, controlled mirror polishing, automated polishing where suitable, and inspection confirmation |
| Whole-cavity profile tolerance | ±0.005 mm can be used as a reference for suitable structures. Final capability is confirmed after drawing review. |
| Curved surface profile | Profile tolerance of ≤5 μm can be evaluated for suitable surfaces and machining access. |
| Opening edge and R corner control | Small edge and radius change is controlled during polishing. For suitable features, ≤0.002 mm can be used as a process reference. |
| Thin-wall cavity reference | ±0.003 mm can be reviewed for suitable thin-wall regions to help reduce uneven wall thickness and local molding defects. |
| Mirror finish | SPI A1 is common for high-gloss charging case surfaces. SPI A0 can be evaluated when the material, depth, geometry, and acceptance standard are suitable. |
| Surface roughness | Ra ≤0.02 μm can be used as a reference for suitable high-gloss appearance molds. |
| Multi-cavity control | Surface state, reflection, size closeness, and polishing balance are checked between cavities according to the confirmed project plan. |
| Quotation basis | 2D drawing, 3D file, mold material, SPI or Ra target, cavity quantity, trial part photos, target quantity, and delivery target |
Final capability depends on the actual drawing. Deep cavities, narrow openings, sharp edges, broad reflective surfaces, micro textures, and hard-to-reach corners normally need a separate process review.
Common Problems in Charging Case Mirror Mold Projects
1. Broad Glossy Surfaces Show Every Small Defect
The charging case has larger visible surfaces than the earbud housing. Light moves across these curves, so tool marks, fine scratches, orange peel, haze, waves, and dark shadows can be easy to see.
A surface may look smooth under normal light but show uneven reflection under a strong lamp or during customer inspection. This is why surface quality needs to be checked from more than one angle.
2. The Opening Edge Can Become Rounded
The opening is one of the most sensitive areas. It affects the visual line between the lid and the lower case. Too much polishing may make the edge soft or change the opening shape.
The molded part may then show an uneven gap, a weak edge line, or a different reflection near the opening. The surface becomes brighter, but the product looks less precise.
3. Deep Cavities Are Hard to Polish Evenly
Charging case molds often include deep inner curves, narrow corners, and transitions between the outside shell and the internal cavity. These areas can be difficult to reach with a stable tool angle.
If the process is not planned well, one area may be over-polished while another remains dull. Local shape change may also affect wall thickness or part release.
4. Upper and Lower Parts Must Match After Assembly
The upper lid and lower case need a clean and even fitting line. A small difference in curve, edge, or parting area can make the gap look wider on one side.
The mold must therefore control both appearance and assembly references. Polishing should not change the surfaces that decide the final lid position.
5. Multi-Cavity Parts May Look Different
In a multi-cavity mold, each cavity may meet its own size requirement but still show a different gloss or reflection. The difference becomes obvious when several charging cases are placed together.
Customers usually need cavity-to-cavity consistency, not only one good cavity. This means the machining, polishing, and inspection method should stay as similar as possible between inserts.
6. Mirror Quality May Drop During Mass Production
The mold surface keeps facing injection pressure, demolding friction, cleaning, and maintenance. Over time, an unstable surface may lose gloss, show pulling marks, or need frequent re-polishing.
A good trial sample is important, but the mold should also support repeatable production. Surface stability and demolding condition should be considered before the mold is released for mass production.
How Yishun Optical Can Help
We review the drawing before quotation and mark the main reflection surfaces, opening edges, deep curves, fitting areas, and places that are difficult to reach. This helps us choose a more suitable machining and polishing route.
Our 5-axis machining capability allows us to work on broad curved cavities, angled opening surfaces, inner transitions, and compact details with fewer unnecessary setup changes.
For mirror finishing, we focus on reducing tool marks, micro scratches, haze, orange peel, wave marks, and uneven reflection. At the same time, we protect the opening edge, R corners, parting areas, and surfaces that control the lid gap.
For upper and lower case parts, or multi-cavity projects, we compare the surface state and key dimensions between inserts. We do not only judge each cavity separately.
We also match the surface strategy to the plastic material and later process. A direct high-gloss PC/ABS part, a coated part, a transparent window, and a plated decorative part may need different mold preparation.
For overseas customers, we use drawings, marked photos, written comments, and inspection records to keep the project clear. This makes it easier to confirm which surfaces need a mirror finish and which areas must keep their original geometry.
Why Choose Yishun Optical
The difficult part of a charging case mirror mold is the balance between a clean high-gloss surface and a precise product shape.
Yishun Optical has long worked on ultra-precision mold cores, mirror mold inserts, five-axis machining, grinding, polishing, and inspection. We understand that a charging case can fail appearance inspection even when its basic size is acceptable.
Our work therefore focuses on the surfaces customers really see: broad curves, opening lines, edge transitions, upper-lower matching areas, and cavity-to-cavity reflection.
By planning these areas before machining, we aim to reduce repeated mold repair, uneven gloss, rounded openings, and sample delays. The goal is a mold that supports both customer approval and stable mass production.
FAQ
1. Can you make custom high-gloss molds for TWS charging cases?
Yes. We can make custom mold cores and mirror inserts for charging case outer shells, upper lids, lower housings, opening areas, inner cavities, trays, and decorative surfaces based on the drawing.
2. Can a charging case mold reach SPI A0?
It can be evaluated. SPI A1 is common for high-gloss appearance surfaces. SPI A0 depends on mold material, cavity depth, surface access, geometry, and the customer’s acceptance standard.
3. How do you protect the charging case opening during polishing?
We mark the opening edge and nearby fitting surfaces before polishing. The polishing path and removal amount are controlled so the edge does not become soft or rounded.
4. Can you work on deep charging case cavities?
Deep cavities can be reviewed. We need to check depth, width, tool access, corner shape, material, and the required mirror level before confirming the process.
5. Can you control multi-cavity appearance consistency?
Yes, but the cavity structure must be reviewed first. We compare key dimensions, surface state, reflection, and polishing balance between cavities according to the confirmed inspection plan.
6. What surface defects can mirror polishing help reduce?
Controlled mirror polishing can help reduce tool marks, fine scratches, haze, orange peel, local dull areas, and uneven reflection. The final result also depends on mold material and the condition after precision machining.
7. What information is needed for quotation?
Please provide a 2D drawing, 3D file such as STEP, IGES, or X_T, mold material, SPI or Ra target, cavity quantity, estimated quantity, target delivery time, and any trial part or defect photos.
8. Can you provide a sample plan and inspection reports?
Yes. After drawing review, we can discuss a sample plan. Depending on the confirmed scope, dimensional reports, roughness records, and appearance inspection records can also be provided.
Get a Quote for a TWS Charging Case Mirror Mold
Send us the project information below. We will first check the opening edge, deep cavity, broad reflection surface, fitting areas, and multi-cavity requirements.
- 2D drawing
- 3D file, such as STEP, IGES, or X_T
- Mold material requirement
- SPI A1, SPI A0, or Ra target
- Cavity quantity
- Sample photos or defect photos
- Estimated quantity and target delivery time