Dry ice cold spray to remove burrs

Molding defects and how to fix them: Understanding mold flash/burrs

”Molding defects reduce the surface quality of rubber and plastic parts. Causes include flow lines, sink marks, vacuum voids, and surface delamination issues. Molding defects are also caused by short shots, burn marks, jetting and warping. Flashing or flashing, the formation of unwanted plastic or rubber on the surface of a molded part, is also common. Dry ice blasting deburring is a batch process technology that offers product manufacturers a cost-effective method to improve surface quality while preserving dimensional tolerances.

Mold flash can affect the surface finish of a part and can also affect sealing. Flashing is often a cosmetic defect, but product manufacturers want to avoid unwanted line burrs from poor quality parts.

During injection molding, plastic or rubber can leak between the mold parting lines. For overmolding, leaks may occur between the substrate and the mold. Mold flashing can also occur during the fill or pack stages. Both traditional and thin-walled parts are susceptible.

Mold flash problem

The causes of glitches can be divided into five main categories:

parting line mismatch

Improper exhaust

Insufficient clamping pressure

Poor Sprue Bushing Support

Viscosity is too low

parting line mismatch

The parting line is the dividing line that separates the two halves of the mold. A mismatch occurs when dust, dirt, contamination, or residue prevents the two parts (core and cavity) from fitting tightly and closing properly. Die flash is also caused by old, worn tooling. During the forming process, the large amount of pressure exerted on the mold surface deforms the metal. Mold flash is also an issue with rubber and plastic parts with complex part geometries. the

Improper exhaust

During rubber or plastic molding, the air contained in the tool needs to escape somehow. Otherwise, the melt will compress and trap air in the cavity. Mold vents support the passage of air, but some vent designs are insufficient. For example, if the rubber or plastic material is stiff, the mold’s ventilation holes may not be deep enough. If the material is fluid, the vent may be too thin. Vents that do not meet the required tolerances or are worn can also lead to flash formation. “

Insufficient clamping pressure

Clamping pressure refers to the force exerted by the molding machine on the mold. Called tonnage, this force must be strong enough to resist the force created by injecting rubber or plastic into the mold. For plastic and rubber injection molding, the pressure generated during the packing phase is sufficient to separate the parting lines of the mold. If the core and cavity separate, flashing occurs.

Poor sprue bushing support

A sprue bushing is a mold component that provides an opening for the transfer of molten rubber or plastic into the cavity. They are made of hardened steel and are designed to accept extrusion nozzles. These bushings help create a more rigid gate through which liquid material is introduced into the mold. Insufficient support for the sprue bushing, however, can transmit stress to the parting line. Thermal expansion in the bushing can also open the mold and cause flash.

Viscosity is too low

Finally, mold flashing can be caused by too low a viscosity—a measure of a fluid’s resistance to flow. When molten rubber or plastic has a low viscosity, they flow quickly and thinly. Conversely, materials with high viscosity flow slowly and are viscous. Viscosity is an effective tool for process optimization, but if the melt temperature is too high, the residence time is too long, or insufficient drying results in residual moisture, flashing may form.

Application of Dry Ice Deburring of Forming Defects

Dry ice deburring of molded rubber and plastic parts removes mold flash from hard-to-reach areas such as cross holes, blind holes, and other complex geometries. Dry ice blast cleaning parts flash removal. This dry ice treatment makes the flash brittle for easy removal without altering the physical and mechanical properties of the part. Also, unlike manual deburring, cryogenic deburring is a semi-automatic process that reduces labor costs.

Dry ice deburring principle

Dry ice cold spray deburring technology

Dry ice pellets are used to mechanically deburr molded parts that have been made brittle by precooling. The impact effect of dry ice particles is used. The cleaning effect is determined by the speed as well as the dry ice particle size and density and the quality of the dry ice. The dry ice pellets transfer heat from the dry ice pellets to the corresponding burrs as they strike the burrs, resulting in a pronounced temperature gradient and corresponding high shear forces in the burrs, which facilitates the removal of the burrs. Finally, dry ice particles sublimate upon impact to produce gaseous CO, which occupies significantly more volume than solid dry ice particles. This explosive increase also gives a pulse to the point of impact, which helps with deburring work.

The dry ice deburring process uses compressed air-accelerated dry ice pellets to remove flashes and burrs from plastic and metal parts. Dry ice sublimates (turns from a solid to a gas) when it hits the surface of the part, so the cleaning process essentially eliminates the need for other media.

The advantages of dry ice cleaning technology deburring lie in the following points:

Dry ice blasting machine online cleaning is safe and environmentally friendly. Dry ice blasting is completely non-toxic and does not use any dangerous chemicals.

In addition to cleaning and safety, dry ice is obtained as a by-product of other industrial processes, and it is made from recycled CO2. It does not produce or add carbon dioxide to the atmosphere, so it has no effect on the greenhouse effect.

Dry ice blasting is safe and completely environmentally friendly!

Reduce cleaning costs, dry ice blasting machine semi-automatic online cleaning, reducing the time and labor costs for a large number of manual cleaning.

Fast and effective dry ice has a very high cleaning speed combined with a wide range of nozzles, which greatly improves the cleaning speed.

TooIce dry ice blasting cleaning can be applied in deburring and deflashing cleaning operations in a more efficient, energy-saving, safer and environmentally friendly way.

Dry ice blasting technology will not lose the finished surface, change the shape or damage the equipment in any way, which can provide the production plant with a more effective cleaning option.

Answers to questions about dry ice deburring technology

How does cryogenic deburring compare to manual deburring?

Tooice dry ice deburring is a safe, clean deburring process and a smart alternative to manual deburring operations. Some machine shops still use hand tools to deburr parts in-house, but manual deburring is time-consuming and labor-intensive. Additionally, workers can only remove a portion of the burr at a time—sometimes with inconsistent results. In contrast, dry ice deburring is a fast, cost-effective, repeatable process that can deburr dozens or hundreds of parts simultaneously.

How do you deburr a precision machined part with hard-to-reach features?

Tooice dry ice deburring is especially effective at deburring blind holes, through holes, and challenging features such as undercuts, grooves, and notches. To meet part-specific challenges, we use non-abrasive media ranging in size from 0.015″ (smallest) to 0.060″ (largest). Before deburring parts, Tooice measures critical dimensions and takes samples. We can save your “recipe” for future batches. If required, we can also create individual matching tooling to improve cleaning efficiency.

What types of materials are supported by cryogenic deburring?

Tooice dry ice deburring can be used on common plastics such as polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET) and specialty polymers such as Delrin®, Teflon®, Tefzel® and Torlon® . However, it is not limited to this as the dry ice deburring method is also used on ABS, CTFE, DAP, HDPE, PEEK®, PPS, Viton® and Nylon. Metal parts made of beryllium copper and precipitation hardening (PH) stainless steel can also be deburred using dry ice.

Which industries and applications use cryogenic technology for precision deburring?

Cryogenic deburring is suitable for precision machined aerospace parts that need to meet critical tolerances measured in thousand inches. Tooice dry ice has also been used to deburr medical devices made from implantable PEEK®, as well as ventilator components used in the ongoing fight against COVID-19. Cryogenic deburring is also a good choice for industrial, automotive and many other applications where precision deburring is required.

Are some deburring jobs too big or too small? What about the turnaround time?

No precision deburring job is too big or too small for Tooice. Whether you need to deburr small batches or hundreds of thousands of production batches, dry ice deburring can save you time and money over manual deburring.

What’s the best way to start?

Ask Tooice to review your technical requirements for precision deburring of machined metal or plastic parts. Consultation is free. If your part is a viable candidate for dry ice deburring, we can perform sample cleaning tests to demonstrate our process. To get started, please communicate with us through the official contact form.

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