Surviving washdown and sterilization

Feb. 1, 2007
After a long day of slogging through food, soaking up citric acid and cooking fat, and chugging down e.coli, how does a high-pressure, foaming chlorine

After a long day of slogging through food, soaking up citric acid and cooking fat, and chugging down e.coli, how does a high-pressure, foaming chlorine bath sound? Ask any motor, encoder, or gearbox and you'll likely get the same answer — no thanks.

When equipment has no choice but to withstand tough washdown and sterilization processes, thoughtful engineers can help their electromechanical workhorses make the best of the battle. Check out these products, tips, and trends from experts on the front line.

Corrosion-resistant chain

Hydro-Service chains are mechanically coated prior to assembly for complete coverage of all surfaces, and can withstand wet, humid, and saltwater environments. Chains will not chip, peel, or become brittle, and contain no hexavalent chromium.

Renold Jeffrey

Sterilizable motor

Series 2057B brushless dc motors come in a sterilizable version for use in autoclave environments, employing a black motor housing for optimum heat dissipation. This 20 mm-diameter motor is ideal in medical and dental handpieces.

MicroMo Electronics Inc.

Stainless steel PC

New stainless steel front plates protect industrial PCs from airborne water particles, with an IP65 rating. PCs handle high-end motion control with an Intel Celeron or Pentium 4 processor on an ATX motherboard.

Beckhoff Automation LLC

Step motor and driver

The αStep AS series has added a splashproof seal to its metal connector to achieve IP65 protection from dust and water. A protective earth ground terminal on the motor case ensures proper grounding.

Oriental Motor USA Corp.

Linear position sensor

C-Series magnetostrictive sensors come in a three-wire option, as a low-cost alternative to sealed cables in wet conditions. Three discrete wires replace the standard connector and cover to allow sealing against wire insulation instead of a cable jacket.

MTS Systems Corp.

Stainless steel linear guides

New linear guide systems made of solid 316 stainless steel stand up to 482° F temperatures, riding on low-friction polymer bearing surfaces. Oil, wear, and maintenance-free, the self-lubricating, corrosion-resistant guides are ideal for chemical washdown environments; several styles and configurations available.

igus inc.

Angular gripper

The 2-finger gripper type LMG 64 meets hygienic design requirements for food handling. Corrosion-resistant stainless steel housing and completely sealed mechanics stand up to harsh conditions.

Schunk Inc.

Cleated conveyor

AquaPruf 7600 series cleated belt end drive conveyors can be disassembled for cleaning — without tools — in 30 seconds. Cleats are molded into belts for increased sanitation. Stainless steel frames, bearings, and housings meet washdown requirements and BISSC certification.

Dorner Manufacturing

“We're seeing a trend toward addressing sanitation requirements before machines are ordered. Project engineers are working with sanitation and procurement on how equipment will be cleaned before it even arrives on the floor. The key is to avoid sanitation problems from the beginning and keep bug counts in check. Special attention should be paid to blind corners on equipment — places that can't be seen and can't be cleaned — where microorganisms can thrive.”
John Kuhnz, Dorner Manufacturing

“The medical handpiece market wants higher performance, while demanding smaller, less expensive brushless dc motors. Designers need to be particularly aware of how motors are sealed because the weakest point is typically the seal around the motor shaft. Especially for autoclave applications, making the motor an integral part of the handpiece usually works best. In order to stand up to autoclave conditions, motors must be equipped with robust components like specially lubricated bearings, stainless steel preload washers, and epoxy treated rather than tape-wound coils.”
Ted Severn, MicroMo Electronics Inc.

DBO ✓list

  • U Think easy to clean, easy to maintain

  • Simpler design means faster, easier cleaning

  • Reduce flat surfaces; make sure they're sloped or perforated for water drainage; round corners where possible

  • Decrease harbor points where water and food particles could collect

  • Make sure moisture doesn't drip, drain, or draw into product areas

  • Mount motors with connectors facedown so liquid runs away; form a “drip loop” in cable below motor so liquid drains off; use splashguards

  • Think about non-porous materials; hermetically sealed hollow parts; solid components; neatly separated wiring; no dead spaces

  • Consider gaskets and O-rings for watertight sealing, especially between connectors and encoders

  • Encapsulated solid-state switches work well on single-phase motors; switches won't corrode or quit around moisture

  • On motors, insulated or encapsulated windings guard against dielectric breakdown from moisture and chemicals; vacuum pressure impregnated (VPI) windings resist electrical shorts

  • Cleaning agents have chemical properties that can destroy seals; learn what will be used and specify seal material accordingly

  • Ditto for metals and plastics — stainless steel and specialized polymers resist corrosion; polished stainless steel reduces metal grooves where bacteria can hide

  • Learn ingress protection (IP) ratings, which grade how well components are sealed against foreign bodies like dust or water; the first digit represents solids protection, the second water ingress, i.e. IP69K offers more protection than IP65

  • Study industry standards, such as: guidelines from the Baking Industry Sanitation Standards Committee (BISSC); American Meat Institute (AMI) — check out their “Sanitary Design Checklist;” 3-A Sanitary Standards (3-A); USDA and FDA requirements

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