The offer: verified engineering substrates
OnlyCases supplies smartphone protective equipment cut and molded from verified raw materials. We refuse to sell mystery plastics, reground post-consumer scraps, or unbranded glass that chips on the perimeter after two days in a pocket.
Our four core production substrates are German Bayer Makrolon optical polycarbonate, 85A and 92A Shore durometer thermoplastic polyurethane (TPU), secondary-tempered aluminosilicate screen glass, and vulcanised medical-grade liquid silicone rubber.
Price basis and material tiering
Every quote is structured by the raw material chemistry confirmed by our Chicago desk:
- Protective cases (20–40 USD each): 85A TPU bumper + optical polycarbonate backplate or liquid silicone with microfiber fleece lining.
- Tempered glass (40–60 USD each): 0.33 mm aluminosilicate glass with double potassium-nitrate ion exchange and 15,000-cycle oleophobic coating.
- Accessories and back covers (15–30 USD each): CNC 6063 aluminium alloy bezels and hydrophobic stainless acoustic mesh.
Quotes are physical specifications verified by Alina Koval; turnaround is same-day or 1–3 business days.
Illinois commercial proof and certification
Our Chicago facility operates under State of Illinois commercial entity registration. Every bulk shipment is backed by verified commercial supply invoices and material test reports detailing Shore hardness, UV yellowing delta-E index, and tensile yield points.
| Polymer / Glass Grade | Primary Application | Hardness / Strength | Failure Mode Prevented |
|---|---|---|---|
| 85A Aliphatic TPU | Impact perimeter bumpers | 85 Shore A / 42 MPa tensile | Corner shock transmission to display edge |
| Bayer Optical PC | Rigid structural backplates | R118 Rockwell / 68 MPa yield | Torsional body flex under pocket pressure |
| Aluminosilicate Glass | Screen protector shields | 9H pencil / 650 MPa flexural | Direct key scratches and edge chipping |
| Liquid Silicone (LSR) | Velvet-touch ergonomic cases | 45 Shore A / 11 MPa tear | Surface peeling, tackiness, lint collection |
| 6063 Anodised Alloy | Camera lens bezel rings | 95 Brinell / 215 MPa ultimate | Direct sapphire lens plate impact shatter |
Why aliphatic TPU durometer matters in Chicago winters
Standard aromatic TPU stiffens below 0 °C, turning brittle and losing 60% of its kinetic impact dissipation. When dropped on frozen concrete at -10 °C, an aromatic case fractures like hard acrylic.
Perimeter bumper formulations use aliphatic polyether-based TPU granules across all impact trims. Aliphatic chains remain ductile down to -25 °C and resist ultraviolet photo-oxidation, eliminating the yellow tint caused by sunlight exposure.
Spectrophotometer UV delta-E measurement
Clear polycarbonate backplates undergo 168 hours of accelerated UVB radiation. Formulations must maintain a delta-E color shift under 1.4 to be catalog approved.
Steel ball drop flexural impact
Screen protectors face a 64 g industrial steel ball dropped from 1.5 meters onto three key zones: optical center, perimeter chamfer, and sensor cutout margins.
Plasma oleophobic abrasion rub test
Tempered glass surfaces endure 15,000 cycles with weighted steel wool (1 kg load). Water droplet contact angle must remain above 105 degrees after abrasion.
Shore durometer needle indentation
Molded TPU bumper rims are tested with a calibrated Type A durometer across ten points along the perimeter to confirm uniform density without micro-voids.