An introduction to powder filling challenges

Weight variation, excess giveaway and product in seal

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VFFS machines are used to pack skimmed milk powder Photo Rovema

Technical article – This is the first of a 10-part series on powder filling and packaging, trends, challenges and solutions

Having set up Hassia in India in 1998 (renamed as Rovema India), I have had the opportunity to deal with diverse types of customers and powders. Packaging powders in general and in flexible pouches in particular is one of the challenging applications.

If you pack powders, or are planning to do in the near future or planning automation, the series of articles may interest you.

Powders are manufactured using a wide range of processes, powders themselves with their diverse physical properties pose specific challenges. You will find here a series of articles that will address various issues and help you develop a to-do list. The real-life experiences discussed below are some challenges faced while filling powders, not necessarily in order of the criticality.

Weight variation

Case 1 Many years ago, we supplied a VFFS machine to pack skimmed milk powder to a private dairy. As is normally the case, excess milk is converted into powder and stored. It is then packed and sold during periods of shortage or supplied to milk deficient areas. 

Packing milk powder therefore falls into two major categories – 

  • Packing inline when milk is getting spray dried or
  • Stored powder or powder bought in bulk packs and packed in retail pouches.

This customer, who packed stored powder, complained that the weight of the pouches is gradually going up over time. Though this came as a complaint, we found the issue outside the machine and in the way the powder was stored. We resolved the issue by writing a SOP for powder storage.

Case 2 In another case, this time a leading brand in the cooperative sector, fresh powder was being packed. A farmer (co-owner in a cooperative) purchased a 1 kilogram pack of SMP (skimmed milk powder) and found it weighed 1,047 grams when the pack weight was 1 kilogram. He lodged a complaint, and I was summoned by the MD of the company. He held us accountable for the excess.

On studying the plant, the problem was found in the feeding system and luckily our team had indicated it during the installation. We helped the customer on order and installed a new feeding system, thereby eliminating the issue.

Case 3 A large MNC packing home and personal care products was approached by us, some years ago, as we had developed a dosing system that could weigh accurately. After a lot of persuasion, we were allowed to evaluate their packaging process. 

We found that the average give away was 15 grams. We could reduce the give away by 6 grams. This resulted in an annual savings of Rs 1 crore (10 million) per annum per machine. This saving was achieved after the customer ordered the first machine. We went on to supply many more machines including to their overseas sites.

There are many hidden savings potentials in the packaging process, which when evaluated with the help of experts can improve efficiency and reduce costs. It is advisable to get an audit done once in two years at the very least.

Case 4 In yet another case, an export customer packing agrochemical powders was fighting with the machine supplier and wanted to return the filling machine. The issue was weight variation. Neither the machine supplier nor the customer could solve the issue. Though the customer was keen to return the machine, the problem was in the product feeding system.

As you can see weight variation and excess give away is one of the key issues in powder packing. It becomes a challenge because the powder properties cannot be a constant. Therefore, the filling and packing must incorporate a strategy to address the issues. These concern not only the equipment but elsewhere too. An objective evaluation is necessary.

Product in seal

Product in seal is another critical issue in powder packing. This can lead to leaking bags and a resultant reduction in shelf life.

Case 1 I was once asked by a senior executive from a FMCG MNC if I was aware of a rodent repellent film. On being asked for details, I was told that rodents were attacking and puncturing the bags.

We studied the problem. The product was a beverage in powder form. It had sugar and other ingredients. The pouch had product in the seal, this let the rodents identify the content and they punctured the bags to get at the product.

By avoiding the product in seal, this problem could be eliminated.

Case 2 Many years ago, a leading beverage and confectionery company called me to see if we could supply a dust proof weigher. They were facing problems with pouch leakages. They warned me that the product is both dusty and hygroscopic.

I offered to visit the plant and understand the problem. On visiting, I found the machine was fully coated with the product, the original colour of the machine could no longer be seen. 

The product was dusty and hygroscopic, as claimed, the customer was facing seal leakages, totally affecting their ability to ship quality products. 

We addressed the problem by suggesting a change in the dosing system. The customer had doubts but we demonstrated and delivered a solution successfully. Now the customer uses our dosing design fully.

Leakages can also be found after a few days of packing, this is a different challenge that can be addressed.

Air in the bag

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K. Ravi is an industry veteran and expert in powder filling, specifically in flexible pouch packaging

Optimizing the cost of primary and secondary packaging involves optimizing the size of the package. This means extracting the trapped air in the product and reducing headspace without having product in the seal. The difference in tap and loose bulk density is often in the range of 20%. One could use several approaches to remove the air.

Summary

Powder packing is a challenge. As manufacturers, we want to supply the right weight, ensure shelf life and deliver on time. The package must also deliver the POP value. We have discussed some of the major challenges associated with powder packaging and you are involved in packing powders, these examples may have resonated with you. This article is aimed at creating awareness and a foundation for further discussion. In the next article we will understand powders in greater detail and how we can address their packaging.

(K. Ravi is an industry veteran and expert in powder filling, specifically in flexible pouch packaging. He played a key role in establishing Hassia in India in 1998, now known as Rovema India. Ravi can be reached at  ravi@raasintelli.com) 

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