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Paint and Coating Stripping with Dry Ice Blasting + Abrasive

We often get asked the question, “Can dry ice blasting remove paint?”  This can be a tricky question as the answer is specific to the situation (type of paint, type of surface, how well is the paint adhered, etc.).

Dry ice is a gentle medium and in some applications it is not successful at removing paint with just dry ice alone.  Depending on the type of paint and primer, even aggressive dry ice blasting can be too slow or too gentle.

Sandblasting

Traditional methods for removing paint and other types of surface contaminants, such as corrosion and paint, are effective but have negative side effects that can become costly and add time to projects.  Sandblasting and other types of media blasting create a significant amount of waste and respirable and environmental dust.  Not only does this require extensive cleanup and containment setup, but it is also unhealthy for workers performing the job.  These methods leave residue and moisture on the surface being cleaned, which requires a second wash and drying time before re-painting or re-coating can begin.

Adding an abrasive to dry ice blasting boosts its’ aggression and effectively removes paint and coatings, while eliminating the issues with traditional methods of removal.

Why dry ice + an abrasive?

When you’re cleaning and preparing a surface, you want to be sure you can remove 100% of the surface contaminants and old paint/coating before applying a new coat – and you want to do so as quickly and efficiently as possible.

Dry ice blasting + an abrasive:

  • Significantly reduces waste and dust generated by traditional methods
  • Does not leave residual media on the surface being cleaned
  • Does not require drying time (no water used in cleaning process)
  • Provides a more environmentally friendly and worker safe cleaning method

Benefits of dry ice + an abrasive

Coating and corrosion removal (1)

1) Eliminates pre- and post-cleaning processes
With the need for containment setup and waste cleanup, methods such as sand, vapor, or slurry blasting are time-consuming and labor-intensive. These methods create a tremendous amount of secondary waste, which means containment must be setup before cleaning begins and when the cleaning ends the secondary waste must be collected and disposed of.In the case of a stripping coating and corrosion from a tank with slurry blasting, containment is setup for water runoff and other waste, which adds time and resources to the project.  When the stripping process is complete, workers must wait for the surface to completely dry before applying a new coat.

Additionally, in saltwater environments soluble solids and chloride accumulates on surfaces, which results in an added pre-wash step that must first be removed before the stripping even begins.

Dry ice + an abrasive limits the amount of time and resources needed for a project by eliminating the need for containment, waste cleanup, drying time, and any post-wash steps. This leads to a considerable amount of hours saved per project.

Also, in the case of saltwater environments, the cleaning can be completed in one step.  Dry ice + an abrasive eliminates pre-washing because the media removes soluble solids and chlorides simultaneously while stripping the paint from the surface.

 

2) Reduces dust levels and waste
As most people know – sandblasting and other traditional types of media blasting generate significant dust and waste. Respirable dust is harmful to the operator, surrounding workforce, the public, and the environment. OSHA has strengthened its standards to encourage initiatives that limit dust exposure. This is one of the reasons for the excessive containment setup required before cleaning with garnet, crushed glass, coal slag, and other blasting methods.

Wet blasting, such as slurry blasting and vapor blasting, uses water with an abrasive to capture dust molecules and keep them from going airborne. While this is effective at reducing dust levels, the method still creates a considerable amount of waste. As well, water as a medium slows down the abrasive particle velocity, which thereby, limits productivity.

Dry ice blasting mixed with an abrasive seeks the best of both worlds. As the dry ice impacts the surface and sublimates from a solid to a gas, that gas suppresses the dust from going airborne due to the fact CO2 gas is heavier than air.

The reduced dust levels also leads to increased operator visibility, which makes it easier for the operator to effectively clean.

 

3) Safer for employees and the environment – Meet OSHA guidelines

Coating and corrosion removal_2

A 97% reduction in dust levels means that the operators and surrounding workforce are not exposed to unhealthy levels of respirable and nuisance dust.  Dry ice + abrasive easily meets OSHA guidelines for dust levels.

Dry ice + abrasive is also a more environmentally friendly option compared to alternatives.  The solution requires significantly less media input than alternative paint and corrosion stripping solutions.  The Cold Jet dry ice + abrasive solution uses 100-150 pounds of media per hour, as opposed to 600 pounds or more per hour from traditional options.  This means that less media and dust is being dispersed into the surround environment.

 

4) Extensive time and costs savings
The dry ice + abrasive mixture eliminates the need for pre- and post-washing, containment setup, and waste collection.  It also cleans faster than many wet abrasive options. This results in a major reduction in project time.

The solution also leaves the surface completely dry and free of residue, which eliminates hours of drying time and allows you to apply a new coat of paint or coating immediately following the cleaning process.

 

When should you use dry ice + abrasive?

1) Heavy or pitted corrosion
coating and corrosion removal 3

If the corrosion is pitted in the metal, dry ice alone won’t be enough to remove that corrosion for proper coating adhesion. With dry ice + abrasive, you can meet requirements for a surface standard prior to the new coating. It will give you a near white metal finish by removing a small layer of the metal and exposing a new metal surface profile.

This is a major advancement for dry ice technology since dry ice blasting has always been non-profile, but by adding an abrasive you can create a profile of 1-5 mL.

2) If dry ice blasting alone just isn’t working
Certain types of paint, corrosion, or coatings simply can’t be removed with the non-abrasive touch of dry ice alone. Depending on the many factors of the surface, dry ice + abrasive is usually best for industrial applications such as structural steel of ships, tanks, infrastructure, tanks and pipelines.

Cold Jet’s dry ice + abrasive solution: The E-CO2 150

cold jet E-CO2 dry ice blaster

The E-CO2 150 combines a Cold Jet dry ice blasting machine (PLT 60, Aero 80 or C100) with a custom 1.5 cubic feet pressurized abrasive pot.The system has been developed specifically to feed Cold Jet’s proprietary mix of dry ice and an abrasive medium.  The custom blast pot enables users to experience accurate dosing of abrasive material, self-regulating capabilities and integration of applicator control mechanisms to ensure dry ice and the abrasive feed together simultaneously when the trigger is pulled.

The proprietary solution has been 3rd party verified to reduce dust levels by up to 97%; thereby, making it safer for the operator, surrounding workforce, and adjacent environment.

The E-CO2 150 also offers a stronger degree of versatility, allowing for non-destructive cleaning with just dry ice and also more aggressive cleaning with Cold Jet’s propriety abrasive mix while remaining environmentally responsible. You can feel confident in knowing that once you pull up to a job that you’ll be able to tackle it with the E-CO2 150.

If you would like to set up an onsite demo or come in to our Tech Center to demo the new machine please contact us.

Photo A dry film lubricant Chemcoaters

DRY-FILM LUBRICANT LEADS TO AHA MOMENT

A little more than 2 yr. ago, the production team at Fleet Engineers, a division of Tramec Sloan in Muskegon, MI, had seen enough. Stamping parts for one of its biggest sellers—frames for mud flaps that go on heavy trucks and trailers—created a mess, as oil applied to the incoming coils of hot-rolled pickled-and-oiled (HRPO) steel drenched its stamping dies and led to huge and costly cleanup issues. Further, downstream welding operations on stamped parts (each assembly comprises nine parts, and measures 12 by 32 in.) experienced excessive weld spatter. Weld quality and appearance suffered, and welders wasted valuable production time cleaning off weld spatter.

“We had to do something to improve the process and to help our pressroom and weld shop become more productive,” says Mike Thorsby, director of supply chain management at Fleet Engineers. “We even had operators stationed at each press using rags to wipe excess oil from the material as it fed into the press. In addition, welders were spending a lot of time cleaning and grinding spatter off of the welds. Further, when we asked the material supplier to cut back on the oil, parts would rust when we sent them out for e-coating and powder coating. It was a vicious cycle.”

Dry-Film Lubricant to the Rescue

The Fleet Engineers division operates out of three manufacturing plants on its sprawling Muskegon campus. Plant one, its 185,000-sq.-ft. metal shop, is where we find the firm’s 16 stamping presses (110- to 600-ton capacities) and weld shop (seven weld cells), where mild and stainless steel, as well as aluminum stock, enter, and truck/trailer parts exit. The metal shop fabricates and assembles mud flaps and brackets, spare-tire carriers, side skirts and other truck and trailer accessories; Fleet also manufactures roll-up and swing doors.

Thorsby files the mud-flap bracket project under the firm’s catalog of continuous-improvement (CI) projects, “to make our products perform better in the field and to improve our processes,” he says, explaining CI initiative goals and objectives. The metal shop produces these brackets at very high volumes, running them for 1.5 shifts/day, 5 days/week. Hence the urgency, in 2017, to improve its stamping and welding efficiency. The solution: investing in the application of a dry-film lubricant (DFL) to each master coil of steel at Chemcoaters in Gary, IN.

“We take in Fleet Engineers’ master coils and run them through our line,” says Ted Jarosz, new product and technical service manager at Chemcoaters. technical sales manager at Chemcoaters. “The steel, 0.059 in. thick, is cleaned using two 30-ft. alkaline cleaning processes and two hot-water rinses. Then the stock runs through a GFG roll-coating line, which applies the DFL (called Chemform), and then finally to an infrared oven for curing.”

Coated coils route to a service center for slitting, then Fleet Engineers runs the slit coils through a blanking line, and press operators feed blanks into the firm’s presses. “We negotiate our steel buy 6 to 9 months out,” Thorsby says, “and have our supplier release the master coils directly to Chemcoaters for slitting and for application of the DFL. It then ships us 10,000 to 12,000-lb. slit coils two to three times/week.”

The Cost Justification Equation

Chemform, an acrylic lubricant with a coefficient of friction of 0.04 to 0.10, says Jarosz, is designed to reduce or eliminate metal-to-metal contact and avoid galling wear. While the process does add about 10 percent to Fleet’s material cost, Thorsby says the benefits far outweigh the additional expense.

“We’ve seen a significant reduction in tool maintenance,” he says. “We’ve also eliminated the use of drawing compound, the need to stage operators at the presses to wipe excess oil from the stock, and post-weld spatter cleanup. In addition, we’ve significantly reduced the time required in our quality department for weld inspection, and the associated costs from rejected parts and reworking.”

While the benefits have been great, Thorsby does note some adjustments made in the shop to accommodate the new DFL. “The lubricant is very slick,” he says. “To prevent the coils from telescoping, we’ve had to add extra strapping bands around the slit coils. And, rather than load blanks onto flat pallets for movement by forklift to the presses, we now stage the blanks on racks—to prevent the blank stacks from sliding off of the truck.”

Wait—There’s More

In addition to the DFL coating, Chemcoaters also offers a coating formulated and blended inhouse, called InterCoat ChemGuard, for use with galvanized substrate and incorporating metallic zinc. According to Jarosz, the coating has a coefficient of friction similar to that of wet lubricants during stamping. It also has a self-healing characteristic—once it becomes damaged, scratched or abraded in service it will still provide corrosion protection along the edges of a punched, sheared or cut edge.

When Jarosz presented the ChemGuard process to Thorsby late in 2018, he immediately thought of the perfect application for another Fleet Engineers product: fabricated tire-carrier assemblies, which are subjected to the harsh environment underneath each truck. Fleet Engineers also switched to the DFL for stamping these parts.

“Stamping these assemblies benefitted from switching to the DFL,” Thorsby says, “by minimizing tool wear and avoiding the need for press operators to sop up excess oil. Taking it one step further, Chemcoaters offers the ChemGuard coating with a few different tints (gray, black and blue) and the black fit right in with the tire carrier. We’re evaluating it with a galvanized sheet steel, replacing the HRPO material, and believe that the color-enhanced ChemGuard product will further enhance corrosion resistance and also eliminate the need for us to e-coat and powder-coat the assemblies. The savings may be significant.” MF

Article Credit: Brad Kuvin & Metal Forming Magazine

Link: https://www.metalformingmagazine.com/enterprise-zones/article/?/Lubrication/2019/8/23/Dry-Film_Lubricant_Leads_to_Aha_Moment