In polypropylene power tool and consumer electronics housings, Barlog Plastics KEBAFLEX SEBS-Comp. S 15 A.01 is evaluated as a low-hardness overmoulding compound for palm-contact surfaces where grip force is distributed over a large area rather than concentrated at an edge. The grade designation encodes a nominal indentation hardness of 15 Shore A under ISO 868 or ASTM D2240; published data for this specific compound is limited, and processing limits are therefore derived from industrial practice for ultra-soft oil-extended SEBS grades. The governing failure mode is adhesive peeling at the polypropylene interface, not cohesive rupture in the elastomer bulk. For a mechanically stable bond, the PP substrate is flame- or corona-treated immediately before overmoulding to raise wetting tension above 38 mN/m, and hot-air preheating is set to 60–80 °C so that the melt interface remains above 160 °C during injection. A fan gate with land thickness of 0.5–0.8 mm is preferred over a narrow point gate, because point-gate shear can generate local temperature spikes and gloss banding in this low-hardness compound. Adhesion is measured to ISO 813 90° peel at a crosshead speed of 50 mm/min and should be repeated on untreated, corona-treated, and flame-treated PP coupons. The injection unit uses a general-purpose screw of 20–25 mm diameter with barrel temperatures from 170 °C to 200 °C, mould temperatures of 20–40 °C, and a cooling time confirmed by cavity-pressure sensors because the part collapses if ejection is attempted while the core remains above the compound’s softening point.

What Limits Demoulding When Shore A15 SEBS Is Injection-Moulded into Undercut Seals?

Demoulding, rather than flow length or shot volume, becomes the controlling process variable when an ultra-low-hardness SEBS compound is formed into undercut closure seals for industrial enclosures. On a two-platen injection moulding machine with a proportional ejector, the low modulus reduces peak ejection force, but the soft surface conforms so tightly to textured tool steel that local vacuum and friction can initiate surface tearing at the undercut. Tooling practice therefore specifies draft angles of 1–2° on polished surfaces and at least 3° on chemically etched or textured surfaces; undercut depth is kept below 0.5 mm per side where a 180° wrap is required. The ejector plate is equipped with piezoelectric force sensors, and the press controller samples their signal at 500 Hz to detect progressive force increase indicating mould fouling or insufficient venting. Mould temperatures are maintained at 20–40 °C; higher temperatures increase surface tack and delay the part’s transition below its softening point, while lower temperatures may produce flow lines at the end of the fill. External release agents are excluded because they contaminate the surface and interfere with subsequent bonding or coating; instead, vacuum-breaking vents of 0.01–0.02 mm depth are cut along the part perimeter. If ejection strain in an undercut exceeds the compound’s measured elongation at break to ISO 37, a split core or collapsing insert is used because the part cannot sustain repeated ejection without visible stress marks or permanent deformation.

Vibration Damping Pads for Compressor Mounts and MEP Isolation

Centrifugal compressors, chiller skids, and mechanical, electrical, and plumbing mounts transmit low-frequency vibration into building structures when rigid metal-to-metal connections are specified. A 15 Shore A SEBS pad is inserted between the equipment foot and the mounting bracket to reduce peak acceleration and shift resonance below the primary excitation frequency. Dynamic stiffness and damping are measured by ISO 6721-4 dynamic mechanical analysis at 1 Hz, 10 Hz, and 30 °C; compression set is measured by ISO 815-1, Method A, after 22 h at 70 °C. The central process conflict is that the very low hardness required for low dynamic stiffness also raises creep and compression set under static preload. For continuous static stress above 0.1 MPa, stress relaxation can exceed dimensional tolerance over several days; published data for this specific grade is limited, so every pad geometry must be tested to ISO 3384-1 at 23 °C and 70 °C. Pads are injection moulded with a thickness from 5 mm to 20 mm; wall thickness above 10 mm increases the risk of internal voids if the screw speed is too high. A screw speed below 80 min⁻¹ and backpressure below 2 MPa reduce air entrapment, but the exact settings are determined by short-shot analysis on the production press. Field measurements on a servohydraulic dynamic test machine show that transmissibility is lowest when the isolator’s natural frequency is below about 0.5 times the primary excitation frequency, but the exact damping ratio must be confirmed because the material’s viscous behaviour changes with temperature and preload.

Orthotic and prosthetic cushioning articles require a combination of low stiffness, repeated compression recovery, and resistance to skin-contact fluids. In this application, KEBAFLEX SEBS-Comp. S 15 A.01 is assessed for cushioned liners, metatarsal pads, and pressure-distributing footbeds, but not for load-bearing structural components or skin-barrier devices. The low hardness is verified by ISO 868; tensile elongation and compression set are measured by ISO 37 and ISO 815-1, respectively, so that the pad’s thickness recovery can be predicted under body mass. Biocompatibility is not established by the base polymer alone: the finished article must be tested for cytotoxicity to EN ISO 10993-5, sensitisation to EN ISO 10993-10, and irritation to EN ISO 10993-23, because processing residues and compounding oils are included in the biological evaluation. Cleaning and disinfection are additional constraints: sustained contact with 70 % isopropanol or quaternary ammonium formulations can extract part of the oil phase and increase tack, so the actual hospital disinfectant must be used in compatibility testing. Processing uses a two-cavity cold-runner tool because hot-runner tips create local overheating at low melt viscosity and can degrade the polymer. Mould temperatures are set to 20–30 °C to reduce tack, and cycle times are longer than those of stiffer TPE grades because the part must be cooled below its softening point before ejection.

When an Ultra-Soft SEBS Compound Replaces Peroxide-Cured Silicone Sheet in Footwear Cushioning

When the design brief imposes replacement of peroxide-cured silicone sheet in footwear cushioning, the substitution is feasible only in midfoot and heel cushioning zones, not in outsole or high-abrasion regions. The SEBS compound can be processed on standard thermoplastic injection moulding machines, but its abrasion resistance and tear strength are lower than those of filled silicone systems; evaluation therefore begins with ISO 34-1 trouser tear, ISO 4649 Method A DIN abrasion, and ISO 815-1 compression set after 24 h at 70 °C. A 15 Shore A part under repeated load loses thickness more quickly than a 30–40 Shore A TPE because the highly plasticised network exhibits lower resistance to plastic deformation. The designed compressive strain should be kept below the point at which returned compression set data exceed the buyer’s tolerance; published data for this specific grade is limited, and no acceptable value can be assumed without testing. Adhesive bonding to EVA midsoles and textile linings is a separate constraint: plasticiser migration can reduce peel strength at the bond line, so the surface is wiped with isopropanol and bonded with a compatible polyurethane primer before peel testing to ISO 813. The injection moulding barrel is typically set from 170 °C to 200 °C, and the mould is held at 20–30 °C; cycle time is governed not by the melt temperature but by the need to cool the part sufficiently for ejection without deformation.

Compression set and creep are not interchangeable in low-frequency isolation

Loading a 15 Shore A SEBS component beyond its proportional limit produces time-dependent deformation that is often misread as product failure. For long-term vibration damping in building services, the part is subjected to a static preload that compresses it by 10–20 % of its free thickness; stress relaxation is measured by ISO 3384-1 at 23 °C and 70 °C. At 70 °C, compression set and stress relaxation accelerate because the entangled styrenic network softens and the oil phase migrates toward the surface. Surface tack can then cause the pad to stick to metal mounting plates, especially when the plates are coated with plasticised PVC or alkyd paints; this incompatibility is managed by interleaving with a polyethylene film or by specifying a fluoropolymer-coated contact surface. The part is preferably compression moulded in a vacuum press at 180 °C for 6–10 min; compression moulding permits thicker sections without weld lines, while injection moulding is restricted to a maximum wall thickness determined by cycle time and void risk. If injection moulding is unavoidable, weld lines should be oriented parallel to the load axis and the part tested for tensile strength to ISO 37 with the weld line in the gauge length.

Extruded edge protection profiles for sheet-metal enclosures are restricted to interior installations because sustained temperatures above 60 °C can accelerate compression set and reduce grip force; exterior exposure requires weathering validation and additional UV stabiliser screening.