Ultrasonic Cleaning Process Design

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Ultrasonic cleaning works well for a wide variety of applications. Often you can simply buy the right size machine, put in the recommended amount of cleaning solution and pick a time, say 10 minutes for cleaning. Ten minutes later, voila! clean parts.

Quick and easy, but also possibly the worst way to get started with ultrasonic cleaning. Here’s why:

You’re wasting time
You’re wasting cleaning solution
You’re wasting power and other resources
Your parts are not as clean be, and may not meet spec (if you have one)
Even if you get good results, you don’t know exactly why, or how improve them

You can avoid all these issues simply by creating your own ultrasonic cleaning process.

Advantages of using a specific process:

Repeatable results
You can meet your cleanliness specifications every time
If something goes wrong, it’s a lot easier to troubleshoot
If you main cleaning employee is out, someone else can step in and use your process
Your documented process can answer questions for other parts of your organization like QC, or management

How to Create Your Own Ultrasonic Cleaning Process

Step 1: How clean is clean?

If you’re going to clean parts, your have to have an objective cleaning specification. By objective, I mean measurable by anyone with the proper equipment.

Examples:

Using 30x magnification on the Zeiss 450 with backlighting enabled, no particulate contamination is visible
When the part is examined under UV lighting, no petroleum contamination is fluorescing
Using our lab’s lint free wipes, a vigorous rubbing of the part produces no visible contamination on the wipe

Not an objective cleaning standard:

Joe in QC says it’s OK

Having a written standard provides multiple benefits:

You know your work is perfect
Other departments know the parts you produce will be to spec
You can always show management exactly what and why you are cleaning this way

Step 2: Creating your cleaning process

This is actually the fun part. If at all possible, start with scrap parts contaminated with the same soil you need to remove. Part damage due to ultrasonics is rare, but why take the chance?

You can check here for papers related to your application:

If your application is not listed above, no worries. Start with the general procedure below.

Let’s get started. The first thing you need is a legal pad, and a pencil.

Write down everything you do.

The idea is that you’re creating a recipe for clean parts. Just like a cake recipe, yours will have ingredients, steps to take, and equipment settings.

Fill your cleaning tank(s), turn on the ultrasonics, and get them up to temperature. A good rule of thumb is to use the minimum recommended amount of cleaning solution, and set your tank to 150 f.

Clean your part for 5 minutes, then rinse and dry if needed, and apply your test for cleanliness.

Did you meet spec?

NO: Increase cleaning time, temperature, or cleaning solution percentage and try again.

*Note – only change one thing per test run. If you increase cleaning solution amount AND cleaning time, you won’t know what worked.

Keep on running tests.

YES: Great, you’re just getting started. Now that you have a baseline, it’s time to refine your process.

One at a time, start tweaking the variables you can control. The goal here is to use the least water, cleaning solution, and electric power possible while still meeting spec.

Here are the variables you have under your control and can change to improve your process:

Time under ultrasonics
Water temperature
Cleaning solution concentration
Parts position/amount in batch

Step 3: Document everything

I can’t emphasize this enough. Not only should every step of your recipe be documented, all your ingredients (cleaning solution, soil, temperature, etc.) should be as well.

Once your process is documented, print it out, put it inside a waterproof sleeve, and attach it to the cleaning system or nearby. If you later change your process, document that as well. Make sure everyone that uses the equipment knows where to find the document and has read it.

So far, so good, but exactly what are we documenting? At a minimum, the following. (Your needs will vary depending on your parts and cleaning specs)

Equipment startup procedures & safety checks
Part SKU and material of construction (steel, aluminum, etc.)
Soil to be removed
Time spent in the ultrasonic tank
Tank temperature
Cleaning solution (MSDS should be attached to your document)
Cleaning solution concentration
Time and temperature of the rinse tank, if one is used
Drying technique and procedure, if any
What happens to the parts after cleaning
Contact info for responsible person

The above will give you want you need from your ultrasonic cleaning system: repeatable results.

If you have any questions, you can always feel free to call me at 877-962-6847, and I’ll be happy to discuss your application, or simply fill out our contact form here.

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