Shot Blasting & Sandblasting: What’s the Difference?
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Understanding the Distinction Between Shot Blasting and Sandblasting
Last Updated: February 27, 2024
If you're new to the world of surface preparation, you may find yourself scratching your head over the difference between sandblasting and shot blasting. At first glance, the terms seem similar, but they represent distinct processes within the broader field of abrasive blasting.
The primary distinction between sandblasting and shot blasting lies in how the abrasive material is applied to the surface being treated. In sandblasting, compressed air is used to propel abrasive materials—traditionally sand—against the surface. On the other hand, shot blasting relies on centrifugal force generated by a mechanical device to hurl the abrasive material at the target surface.
Interestingly, the term "sandblasting" is somewhat outdated. Today's abrasive blasting industry rarely uses sand due to its drawbacks. Natural sand contains impurities and poses significant health risks when inhaled, leading to respiratory diseases such as silicosis. Instead, modern alternatives like mineral, metallic, glass, plastic, and even organic materials (like corn cobs and walnut shells) are preferred.
Why Sand Is No Longer Common in Abrasive Blasting?
Historically, sandblasting dominated the abrasive blasting landscape because sand was abundant and easy to access. However, sand had inherent issues that made it challenging to work with effectively. For instance, sand often contained moisture, making it difficult to distribute evenly using compressed air. Additionally, natural sand supplies were laden with contaminants that could interfere with the blasting process.
Most importantly, sand posed serious health risks to workers. The silica in sand is hazardous when inhaled, potentially causing severe respiratory illnesses. Recognizing these dangers, regulatory bodies like the U.S. Occupational Safety and Health Administration (OSHA) have implemented stringent guidelines to limit the use of silica sand in abrasive blasting. Familiarize yourself with these regulations by reviewing OSHA's fact sheet on "Protecting Workers from the Hazards of Abrasive Blasting Materials."
Beyond its health concerns, sand is limited in versatility compared to contemporary abrasive materials. Sand is restricted to the compressed air blasting method, which lacks the flexibility offered by the centrifugal/mechanical approach used in shot blasting. Nonetheless, the choice between these methods ultimately depends on the specific requirements of your project.
What Is Sandblasting?
Regardless of the abrasive medium, the term "sandblasting" refers to the process of propelling that medium with compressed air. This cleaning and preparation technique utilizes compressed air as its power source, directing a high-pressure stream of abrasive material toward the surface being treated. Whether it’s cleaning dirt and grease from auto parts, refurbishing rusty chains in a shipyard, or prepping old filing cabinets for powder coating, sandblasting serves as a reliable pre-finishing method.
Over the past century, sandblasting equipment has undergone remarkable advancements. Early setups produced uncontrollable, dusty environments, whereas modern systems feature enclosed, highly-controlled enclosures with precise abrasive stream management. Furthermore, the abrasive media used in sandblasting has evolved from traditional sand to more user-friendly materials like aluminum oxide and silicon carbide.
Despite these improvements, sandblasting remains the most popular and cost-effective method for preparing delicate and sensitive surfaces. Its adaptability, affordability, and ability to deliver high-quality results make it an ideal choice for numerous applications.
What Is Shot Blasting?
The term "shot blasting" pertains to the process of propelling abrasive material with centrifugal or mechanical force. Unlike sandblasting, shot blasting operates on a different pressurization system. This method uses a device akin to a spinning wheel to accelerate shot-like materials and blast them against a surface.
Shot blasting represents a more aggressive abrasive technique than sandblasting. It's typically employed for large-scale projects requiring substantial force and dense media to clean and prepare surfaces. Due to its intense nature, shot blasting demands strict containment to prevent collateral damage.
In industrial settings, you'll often encounter shot blasting in scenarios involving heavy-duty tasks, such as restoring automobile frames or recycling steel containers. It's also commonly used in metallurgical applications, like peening engine components to enhance malleability. Shot peening, a related term, refers to the process of pounding metal to improve its strength and durability, which aligns closely with the principles of shot blasting.
Which Is Better – Sandblasting or Shot Blasting?
Deciding whether sandblasting or shot blasting is superior depends on several factors, including the surface being treated and the desired outcome. Sandblasting generally offers a gentler and less invasive abrasion process. However, this can vary depending on the air pressure used and the selected abrasive material. The softer nature of sandblasting makes it more forgiving, allowing for the treatment of sensitive surfaces with minimal risk of damage.
For example, sandblasting proves invaluable when cleaning delicate electronic parts or connectors affected by corrosion. With the right combination of low pressure and soft media (such as organics or glass), you can achieve excellent results without compromising the integrity of the surface. If you require more aggressive abrasion, silicon carbide serves as an excellent alternative to aluminum oxide.
On the flip side, shot blasting excels when dealing with denser materials requiring deep abrasion. While sandblasting might prove insufficient for preparing gears and shafts, shot blasting can efficiently clean thick and heavy surfaces like metal hulls and truck hubs. Shot blasting typically employs robust media like steel shot and steel grit, which deliver powerful impacts to remove stubborn rust and pollution.
Ultimately, the decision between sandblasting and shot blasting should rest with experienced professionals who understand your project's unique needs. While sandblasting offers speed and affordability, shot blasting provides a more comprehensive treatment with advanced equipment. Consequently, shot blasting tends to be slower and more costly than sandblasting. However, certain tasks necessitate the precision and strength of shot blasting, leaving sandblasting as an unsuitable option.
Equipment Used in Sandblasting
Sandblasting relies on high-pressure compressed air to propel abrasive media onto the project. This dependable technique accommodates a wide array of surfaces and treatment types, utilizing various abrasive materials. Sandblasting equipment removes contaminants such as rust, grease, and old paint to enhance surface adhesion for new coatings. Key components of sandblasting systems include:
Equipment Used in Shot Blasting
Shotblasting employs wheel blast equipment to propel abrasive media onto surfaces being treated for final finishing. This equipment uses a specially designed wheel to generate centrifugal force and blast materials like steel shot and steel grit onto products. The process involves "throwing" media at a surface rather than "blowing" it. Common shot blasting equipment includes:
Selecting Abrasive Media for Sandblasting and Shot Blasting
Both sandblasting and shot blasting systems rely on both basic and advanced equipment designs. However, neither system would function without abrasive media, which serves as the core of the abrasion blasting process. Available in various forms, each type of media is tailored for specific applications.
In air blast systems, media enters the compressed air stream from a pot or container. Valves channel the media into the blast hose, and a recycling system ensures the media returns for reuse. Similarly, centrifugal shot blasting systems have a holding container that uses a mechanical feed to send media into the spinning wheel and onto the treatment surface before collecting and recycling it.
Abrasive materials can be mineral, organic, ceramic, plastic, or metal-based. Each chemical composition performs specific abrasive tasks and possesses key abrasive properties. When selecting abrasive media for sandblasting and shot blasting, consider these four essential properties:
Sandblasting and Shot Blasting Abrasive Media Materials
Each type of sandblasting and shot blasting abrasive media has unique qualities beyond shape, size, hardness, and density. Media selection primarily depends on the surface being prepared rather than the type of equipment used. Here are common abrasive media materials found in sandblasting and shot blasting operations:
Choosing Between Shot Blasting and Sandblasting
This guide provides insight into the intricacies of sandblasting and shot blasting operations. The primary distinction lies in the type of equipment used, along with a wide range of abrasive media options for both processes. Determining the exact system and media for a specific project is best left to professionals.
Finishing Systems stands out as your premier choice for professional sandblasting and shot blasting services. Located centrally in York, PA, we've been operating since the early 1970s, building the expertise, skills, and experience necessary to handle any finishing job you require.
To learn more about sandblasting and shot blasting services or to determine the best abrasive media for your project, call us today at 800-582-3693 or contact us online.