Description:

The PNMF series EVA slipper and sandal scrap pulverizer is configured for processing the offcuts and waste generated in slipper, sandal, and open-toe footwear manufacturing — a distinct material category from injection-moulded sports shoe soles covered on the EVA Shoe Sole Pulveriser page.

Higher VA content — more heat-sensitive. Slipper and sandal outsoles typically use softer, higher-VA-content EVA (22–35% VA) compared to the 14–20% VA used in running shoe or dress shoe midsoles. Higher VA content lowers the EVA’s softening point further toward 55–65°C. On the PNMF, this means the disc temperature threshold is narrower, feed rate must be reduced more significantly, and an external chiller is more commonly required than for standard shoe sole grades. When switching from shoe sole EVA to slipper sole EVA on the same machine, the operator reduces disc speed (via frequency converter) and feed rate before the first run to avoid sticking.

Mixed-colour scrap — powder downgrade. Slipper and sandal production typically involves a wider colour range than standard shoe soles, and colour-change scrap — the mixed-colour material produced during colour transitions or accumulated from multi-colour production runs — cannot be reintroduced into a single-colour slipper compound. Mixed-colour EVA offcut powder is typically downgraded to: foam board and yoga mat compound (where colour variation is not visible in the finished product), EVA foam sheet filler, or garden slipper compound (typically black, masking colour variation). Pre-sorting scrap by colour before pulverising and collecting powder batches separately maximises the reintroduction ratio of single-colour batches.

Pre-granulation required. As with all moulded EVA sole types, slipper and sandal offcuts must be reduced to ≤3 mm by a crusher before entering the PNMF. For full machine specification and component details, see the EVA Shoe Sole Pulveriser page.

Technical Features:

For full Technical Features of the PNMF platform, see the EVA Shoe Sole Pulveriser page. Key differences when processing slipper and sandal EVA scrap:

1. Reduced disc speed and feed rate for high-VA EVA (22–35%) — frequency converter adjustment is required when switching from standard shoe sole EVA (14–20% VA) to slipper/sandal grades; higher VA content reduces the safe operating temperature margin and requires lower throughput to maintain disc temperature below the sticking threshold.
2. External chiller more frequently required — for continuous processing of high-VA slipper sole scrap, particularly in ambient temperatures above 25°C, the external chiller connection is the recommended configuration rather than an optional accessory.
3. PLC colour-batch presets — saving separate operating parameters per colour batch reduces setup time when processing multiple colour runs in sequence and helps maintain separation of single-colour powder batches for maximum reintroduction value.

Components:

Vibratory Feeding Calibrated for pre-granulated EVA slipper scrap (≤3 mm); set to lower feed rate than standard shoe sole EVA to accommodate higher-VA-content grades.	Pulverizer Disc Fixed disc water-cooled cavity + rotating disc atomised spray cooling; both essential for high-VA slipper sole material. Disc speed reduced via frequency converter for VA content >20%.
Whole Body Pulverizer Blade Standard for PNMF-300 to PNMF-500; customisable for high-VA slipper sole grades. See EVA Shoe Sole Pulveriser page for full blade specification.	Segment Pulverizer Blade For PNMF-600/800; resharpenable 4–5 times — cost-effective for continuous slipper scrap recycling across multiple colour batches.
Temperature Control Thermostat threshold set lower for high-VA slipper sole EVA than for standard shoe sole grades; automatic feed pause triggered earlier to protect material and disc surface.	Vibrating Screen 20–40 mesh standard for slipper compound reintroduction; 40–60 mesh for foam board or exercise mat filler applications. Interchangeable screen mesh.
Bags Type Dust Catcher Standard option; pulse dust collector recommended for facilities processing high-VA EVA in enclosed workshops.	Intelligent Control PLC panel with colour-batch-specific presets for disc speed, feed rate, and temperature threshold — allows sequential processing of multiple colour batches with consistent quality per batch.

Application Areas:

Single-colour slipper/sandal offcut recycling. Pre-sorted single-colour slipper and sandal sole offcuts are granulated and pulverised to 20–40 mesh for reintroduction into the corresponding colour EVA slipper compound at 10–20% addition. Single-colour batches maintain the highest reintroduction value.

Mixed-colour scrap powder — downgrade applications. Mixed-colour EVA slipper scrap (from colour transitions or accumulated multi-product waste) is pulverised to 20–40 mesh for use in foam board compound, exercise mat production, or garden slipper compound where colour consistency is not a requirement. This keeps mixed scrap in productive use rather than disposal.

Outsole and thick-sole offcut processing. Thick EVA outsoles (10–25 mm, as used in platform sandals and cushioned slippers) generate larger offcut pieces that require more aggressive primary crushing before the PNMF stage. The PNMF handles the resulting granules at the same mesh targets as thinner sole offcuts.

Frequently Asked Questions

Why does slipper and sandal EVA require different machine settings than shoe sole EVA?

The primary difference is VA (vinyl acetate) content. Shoe sole EVA for running or dress shoes typically contains 14–20% VA, giving it a relatively firm texture and a softening point of approximately 70–80°C. Slipper and sandal sole EVA typically contains 22–35% VA for a softer, more flexible feel — this higher VA content lowers the softening point to approximately 55–65°C. On the PNMF disc grinder, this 10–15°C narrower safety margin means the disc temperature threshold must be set lower, the feed rate reduced, and the frequency converter used to lower disc speed compared to standard shoe sole processing. An external chiller is more frequently required for continuous slipper sole processing, particularly in warm ambient environments.

How should mixed-colour EVA slipper scrap be handled?

Mixed-colour scrap — the EVA material produced when multiple colours are processed on the same line, or where different colour soles are accumulated together — cannot be reintroduced into a single-colour slipper compound without affecting colour consistency. The standard approach is: sort scrap by colour before granulating and pulverising where possible; collect single-colour powder batches separately for same-colour compound reintroduction; collect mixed-colour scrap in a separate bin for downgrade applications (foam board, exercise mat compound, or black garden slipper compound). The powder from mixed-colour batches is still fully usable — it just needs to go to an application where colour variation is not visible in the finished product.

How does this page differ from the EVA Shoe Sole Pulveriser page?

Both pages cover the same PNMF platform. The EVA Shoe Sole Pulveriser page covers standard injection-moulded and compression-moulded shoe sole material (VA 14–20%, full machine specification, model selection guide). This page covers the specific considerations for slipper, sandal, and outsole scrap — higher VA content (22–35%), the resulting need for lower disc speed and stronger cooling, and the mixed-colour scrap management that is more common in slipper than in shoe sole production. Machine specification and model selection are the same; the operating parameters and scrap management workflow differ.

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