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Plungers and filter

Part of the Collection section. Filter tube, plug cutter, and plunger interface (wear, sealing, and CIP cleaning).

Introduction

The filter tube and plug cutter define the juice filtration path and the core-ejection path. Plungers pass through the filter tube during the cycle to eject the core and scrape pulp from the slot region. This subassembly is sensitive to surface finish, alignment, and sealing; current designs are based on the commercial machine but with increased length and higher industrial load/pressure expectations.

Colour key & components

Key components and intent (colours may vary across CAD figures).

Figures

Filter/plug-cutter context is shown in the Collection main gallery. Add dedicated closeups here later (ID finish callouts, slot geometry, seal detail, plug-cutter attachment).

• Add figure: filter tube slot pattern and how scraper clears pulp each cycle.
• Add figure: plunger-to-tube sealing concept (current vs proposed O-ring/lip seal).
• Add figure: plug cutter attachment options (integral vs removable tip).
• Add figure: reverse-flow CIP path exiting plug cutter centreline.

Discussion

Rough design & intent

• Commercial baseline — Filter tube and plug cutter are based on the commercial machine geometry; industrial version increases length and expects higher loads and higher pressure during extraction.
• Finish & sealing — Filter tube ID should be ground/polished (Ra ~0.8 μm concept) so plungers slide smoothly and a seal can be achieved.
• Material — Intent is hardened steel for filter tube and plug cutter (vs prior 304) to reduce wear from scraper action.

Known issues & risks

• Leakage — Known issue: juice leaks past plunger-to-tube interface. Current plan is surface-to-surface sealing; likely needs an O-ring or alternative seal for industrial pressures.
• Wear — Scraper action can roughen tube ID if materials are not chosen correctly; heat treat/finish must be validated.
• Alignment — Tube is welded to a cap and then assembled; weld and assembly stack-up can misalign plungers, increasing leakage and wear.

DFM & manufacturing (China)

• Slotting — Laser cut slot pattern (0.7 mm slot width concept) in hardened steel tube; contractor to propose manufacturing route and inspection.
• Heat treat + finishing — Contractor to propose hardening and post-grind/polish methods that keep tube straightness and slot geometry within tolerance.
• Assembly — Contractor to propose how to weld cap without distorting tube, and how to control tube axis alignment through assembly.

Questions for contractor

1. Propose a sealing solution for plunger-to-filter tube suitable for high pressure and washdown (O-ring groove, lip seal, or alternate geometry).
2. Recommend material/heat treat/finish for filter tube + plug cutter + scraper, with expected wear life and maintainability.
3. Recommend whether plug cutter should be integrated with the filter tube or remain a removable tip, considering sanitary rules and service.
4. Propose an inspection and acceptance plan for the tube (ID finish, straightness, slot quality) and for assembled plunger sealing performance.

Interfaces

• Input: Juice exits fruit into filter tube slots; plunger enters tube for core ejection and scraping.
• Output: Juice to collector; core ejected through plug cutter to disposal; CIP reverse-flow exits plug cutter centreline.
• Mount: Filter tube and plug cutter mount on the collection assembly and interface to core ejection plungers.

Interfaces and tolerances

Known interfaces and tolerances. Links go to related subsystems.

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