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Food for thought

In the global food production industry, challenges surround meeting the sanitary requirements for weld areas on food processing equipment

4Many manufacturing industries have to manage up and down cycles with the exception of the food production industry, which can be considered virtually recession-proof. Everybody has to eat, and most modern economies rely on processed food to feed the masses.

surface conditioning with pferd
Surface conditioning on stainless steel (Inox) with a unitized CombiDisc.

Plenty of statistics highlight the sheer size of the food production industry. Worldwide, Research and Markets, a Dublin-based market research company, reports that the global packaged food market will reach $3.03 trillion by 2020. As a specific example, specialty markets, such as cheese; packaged, ready-to-eat refrigerated entrees; and coffee, sell $120.5 billion in today’s U.S. marketplace alone, according to the Specialty Food Association.

Farm to table

Several areas are involved in the manufacture and processing of food products: the equipment used to plant and harvest the food; the equipment used to improve the quality of the yield, distribute the pesticides and for the cleaners used on the processing equipment; and for the equipment used in the actual processing plants. These areas make up the basics of the food production industry and each entails specific finishing processes for cosmetic and sanitary requirements.

To manufacture agricultural equipment, cosmetic finishing is a primary issue because it helps to extend the life of the equipment exposed to the hardships of planting and harvesting. However, the equipment manufactured for the food processing industry, much of it made of 304 stainless steel, is the focus of the National Sanitary Foundation to set standards and reduce risk of bacterial issues. These standards are key for the USDA and FDA agencies’ inspection procedures.

Because food is a perishable item, the food processing timeline is critical. The collection in the field as well as the transportation of the food product to the processing plant all contribute to the potential of lost revenue from spoiled or damaged product. The process of cleaning, slicing, cooking, flash freezing and packaging calls for an uninterrupted flow of product and process.

Food processing equipment is designed for safety during use, but must also allow for a full breakdown of the inside of any machine. This is critical so that daily required cleaning can reach all significant areas. To reduce the potential for pathogens in the food, constant sanitation and daily full-plant cleaning is a must. All equipment must be designed to allow for a full cleaning of all surfaces that will come in contact with raw food.

Therefore, the equipment inside and out must be able to withstand solutions of caustic or acidic cleaning products on a daily basis. The National Sanitary Foundation is very specific on the requirements for the finishing of food processing equipment in all types of plants. This is often not a cosmetic issue, but is instead an issue of sanitation in the processing of food product.

Clean sweep

The focus for offering a finishing system that works requires an understanding of the relationship of finishing products based on speed and pressure as well as the ability to offer a simple system to achieve the desired result in three main locations on the food processing equipment: weld blending on inside fillets, blind corners and lap joints.

The sanitary requirement for OEMs is to blend all welded areas that may come into contact with food product to a depth of scratch equal to a 150- to 180-grit abrasive product (Ra = 30 to 41 micro in.) with no undercut to the parent material.

It has been determined that when the welded areas meet the required depth of scratch, normal cleaning and sanitizing procedures will reduce the chance of bacteria collection and growth in those areas. However, there is no requirement for a cosmetic scratch pattern, such as a linear finish to meet the specification.

As all food processing equipment is cleaned at least every 24 hours if not more, the cosmetic finish is often more of a hindrance due to the continued maintenance. As a result, the challenge is to design a finishing system for both the OEM and the end user that is simple in application but consistent in results. The system must leave no potential contaminant behind that might present issues for premature failure at a later date.

Many companies offer abrasive products that require multiple steps to achieve the required finish. Some offer expensive equipment designed for spot cleaning and instant passivation of welded areas. The expectation is that all stainless steel must receive help to achieve a stable state of passivation after the fabrication process of welding. Passivation is, essentially, the state of being resistant to corrosion.

However, passivation is a natural occurrence and is easy to achieve based on the requirements of ANSI A967 and A380 specifications. Using the proper abrasive product that is designed for use with stainless steel is a must. Following a prescribed procedure based on controlling friction and heat offers the most cost-effective process for finishing stainless steel for food processing use.

The daily cleaning of stainless steel food processing equipment and the exposure to oxygen in the air and water used allows the chromium oxide layer to constantly reform and passivate the material. So the challenge is to control the friction (heat) and possible surface contamination during the fabrication process along with the removal of excess weld material.

weld seam polish
Polishing a weld seam on stainless steel (Inox) sheet metal using a Pferd felt polishing point.

Process parameters

The process starts with defining the required finish in a given area. Because the official final finish is already defined, the main issue is on the part of the equipment manufacturer for an additional “signature finish” over and above the minimum. This finish is more for the cosmetic requirements to sell a new piece of equipment. As long as the desired final finish is defined with abrasive products equal to the specified Ra parameters, extra time and money may be dedicated to offer a finish that meets sanitary requirements that is also pleasing to the eye.

The maintenance of that finish is not as important to the actual food processor because often new equipment finishes are not maintained during the actual food process cycle. Linear “brushed” drum finishes (Pferd 91217 system), non-directional “D/A” finishes (Pferd 47564 disc) and even “mirror” full reflective finishes (Pferd 48705 felt disc with 48763 paste) are beautiful to look at on new equipment, but difficult to maintain in a real food processing environment. Pferd, therefore, offers a maximum three-step solution to achieve these cosmetic finishes on a MIG or TIG weld surface.

However, the real need is for a solution to maintain the equipment while keeping the food product flowing. This need for a fast and efficient method for maintenance and repair applies to everyday feed trays, carts, shuttle systems and food grinders damaged in the daily processing of food product.

A good combination

Pferd designed the CombiClick, CombiDisc and PoliCap families coupled with the company’s variable-speed right-angle and straight-shaft power tools to deliver a complete finishing system that addresses the three major finishing areas – weld blending on inside fillets, blind corners and lap joints. All the consumable products are designed and cleared for use on all metals, including stainless steel.

pferd weld finishing

Mating a power tool and the consumable allows for the recommended speed to optimize the performance of the consumable and achieve the desired result, requiring the least amount of time and effort. Pferd’s solutions are often able to blend a weld from a MIG or TIG process to the desired sanitary finish in only two steps. The CombiClick family of quick-change discs, used with the Pferd 91205 variable-speed right-angle electric grinder is ideal for weld blending in butt and lap joints. Using the 80-grit Co-Cool coated abrasive on the special scalloped backing pad allows for quick and effective excess weld material removal and sets the stage for the unitized or non-woven disc for the final finish.

The CombiDisc quick-change system with the Pferd 91200 variable-speed power tool offers a mini PoliFan disc for material removal in tight areas, with the second step again being the unitized or medium non-woven disc. Pferd offers a hard and a soft version of the medium non-woven disc to achieve excellent contact with tight areas around fittings and support brackets.

Pferd’s PoliCap abrasive caps range in sizes from 3/16 in. diameter to a direct point. Combined with the Pferd 91005 variable-speed straight-shaft power tool, it allows blending contact even to a tight inside corner.

Many times the requirement is to repair the affected area so production can continue while maintaining the sanitary requirements the FDA and USDA demand and consumers expect. To adhere to those regulations and expectations, Pferd’s finishing systems are designed as a total solution to be faster and more cost effective for the fabrication, repair or maintenance of new and used food processing equipment. Time is money, and with the sensitivity of food production, maintaining the flow of clean and safe food products is important to every consumer.

Pferd Inc.