Custom Processing Services Blog

Contract Drying Services — The 5 Keys You Need To Know

Justin Klinger, May 22, 2020 9:29:58 AM

The 5 Keys To Contract Drying Services

Is your company in this spot?

You’ve developed a great far. It just requires some help with a critical part of the production process — drying. So you’re looking to outsource that task using a company with specialized drying equipment, dedicated facilities, and skilled labor.

However, you have no idea how to find them. So, like any modern American, you begin your search by Googling “Contract Drying Services.”’s a start!

So, you find dozens of toll processors (a company that handles outsourcing services), yet none clearly stand out; maybe because you’re not exactly sure what toll drying method is best for your drying needs.

This article will walk you through the process of finding an experienced, reliable toll processor to provide you with the right contract drying services. First things first...

What is a Toll Processor?

Before diving into contract drying services, let’s briefly review toll processing. 

We’ve tackled this question in a previous article, but here are the basics: a toll processor’s experience in processing many materials provides clients with process suggestions, insights on challenges, and specific formula advice to reach exact physical and chemical compositions.

One of the services toll processors offer is drying. Others likely include milling/grinding, blending, extraction, extrusion, separation, and more.

Whatever service is performed, the right toll processor customizes formats, coordinates logistics, increases efficiency, enhances quality, reduces headaches, saves money, and more. Yes, a toll processor can be a real life-saver...if you choose wisely; picking the wrong toll processor for drying can have long-term negative consequences in both product quality as well as your bottom line.

OK, now let’s explore contract drying services specifically and cover the 5 keys you need to know.

1. Material Considerations

To help narrow down what type of drying method to use (and who should do it), the initial focus should be on the material itself.

First, look at the size of the individual particles being dried and the material’s density, which affects how it moves through a dryer. Second, determine the starting moisture percentage and the ending moisture percentage goal; the water weight to be dried is used to choose the dryer size.

Some materials, upon reaching a certain temperature, react to heat, which could be melting or burning or creating a chemical reaction. This will determine if the dryer needs to be large and slow, meaning a lower temperature is needed to dry it, or if quick, high heat is possible.

Next, consider if the material is sludgy and/or sticky, needing to be forced through the dryer, and if the material is fragile or abrasive. Now, think about the quantity of material expected; can dryers handle running continuously or is batching needed?

The right toll processor will work to examine all of these material considerations. Only then will you feel good that your decision on your contract drying service partner is the correct one and that you’re using the best toll drying method to meet your required moisture specification.

2. Material Testing

This could be the most important key. The only sure way to know if a material is right for a dryer is to test a sample. And the only way to be certain that your quality and quantity requirements will be met is if the drying method is properly tested, too.

Here’s an example: An operator examines the physical properties of the sludge material knowing it needs to be small enough to disperse and convey throughout the dryer. After seeing the desired moisture percentage goal, the operator calculates the dryer’s ability to handle and heat the material. After the material is run through a dryer, the operator uses a table-top device to calculate the sample’s moisture content.

Testing the material on the drying equipment ensures that the process properly takes the wet, beginning material and produces a dry, final product that nails moisture specifications.

3. Drying Methods

There are several ways to potentially dry a material, and it’s easy to get confused about all of the available drying methods. Toll processors’ contract drying services rely on various industrial drying equipment (more on those below), which dry in different ways.

The flash drying process uses low-pressure jets of hot air to reduce moisture, break down the material’s size (to within specification), and provide deagglomeration. A recirculating loop produces dry, discrete particles from powders, centrifuge cakes, or slurry feed. Read this article for more details on flash drying.

Fluidized bed drying subjects solid particles to conditions that cause them to behave like a fluid. When air flows through a perforated distributor plate, it supports the particles (larger than 50 microns) and dries them. 

Similar to the other two methods, spray drying uses suspended particle processing. The difference: when the liquid is sprayed through a nozzle, it forms tiny droplets, which are hit with hot air, causing them to dry.

4. Equipment

When you work with a toll processor for your contract drying needs, you may not be too concerned about the drying equipment they’re using. As long as the material is dried correctly, right?

Sure, but it’s always a good idea to get familiar with the equipment so you can properly evaluate a toll processor. You need to know that your capacity will be met and your quality standards upheld.

For instance, a 6-inch flash dryer handles 3- to 4-truckload quantities, while large-volume jobs require a flash dryer as large as 14-inch. Also, look for fluidized bed drying equipment that’s fully adjustable, with a large drying temperature range that can maintain product particle size and shape.

As dedicated as the toll processor may seem, without the right equipment, you won’t meet your goals.

5. Choosing a Partner

Here’s a thought: your toll processor is likely the final quality control gatekeeper between your product and your customer. Quality isn’t something you can sacrifice, so take a long look at this list of measures that reflect a toll processor’s drying performance.

  • The ability to meet moisture specifications; after all, that’s what drying is all about
  • Material that arrives contamination-free; by nature, toll processors are obsessed with cleanliness
  • Certifications mean a lot; being ISO 9001:2015-compliant, following cGMP guidelines, knowing FSMA standards, being PCO-certified...any reputable toll processor will have these and more
  • The ability to trace product from arrival through departure is standard procedure for any worthy toll processor; make sure yours can do that
  • An understanding of all drying techniques; choose a toll processor that has mastered many drying methods
  • Pride in delivering material consistently on time and within quality packaging and at the quoted price

Reviewing a toll processor’s quality control procedures is important, yet having a discussion about their company values and priorities could tell you even more. You’ll get a good feel if they’ll be just a supplier or a true partner.

Now, you’ve got a great start in choosing contract drying services that meet your quality, budget, and delivery needs. You know the right toll processor gives you a huge and immediate advantage, but are you wondering how toll manufacturing is similar or different than contract manufacturing? Read our guide, Differences Between Toll Manufacturing & Contract Manufacturing. Just click the image below to get access.

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Posted in:Drying