If your factory safety measures aren’t safe, how safe will the operators be? And if the crew can’t trust the machines they work with, how can customers trust the end product?
The requirements of machine guarding are to ensure output quality and protect your crew from sparks, flying debris, pinch points, and rotating components. Yet some facilities break almost every machine guarding safety rule in OSHA’s book. You can blame much of it on subpar T-slot framing materials and engineering:
|
Rules of Guarding |
Reality of T-Slots |
|
“Prevention of contact” |
Offers little resistance to unexpected forces |
|
“Be secured in place” |
Loosens and weakens with vibration |
|
“Create no new hazard” |
Obstructive; safety sensors may misalign |
|
“Not interfere with machine operation” |
Workers ignore warnings; added downtime for maintenance |
It’d be funny … if it wasn’t scary.
Your initial reaction might be, “OK, then use steel guarding,” which in some cases is a sufficient machine safety solution. However, steel framing creates a few risks of its own.
Fortunately, there’s always time and budget room for safety. Review these six design factors in industrial guarding that may become failure points – unless you dedicate yourself to a solution:
When it comes to shop floor safety, industrial machine enclosures and guarding should be part of the solution, not the problem. Watch out for several design and environmental risks that can render protocols useless:
Traditional T-slot framing systems, made of extruded aluminum, are a common sight in CNC and other machine enclosure applications. They’re popular because they’ve been around forever, are cheap, and are modular.
They’re also sadly ironic, because a T-slot guarding frame likely isn’t stopping anything. It creates an illusion of safety, but not much of a real one – like the “Keep Away” fence at Jurassic Park.
Operations in a fixed location need machine safety fences that are actually secure enough to prevent unwanted movement. If you visit 10 factories with guarding today, chances are five will be using T-slotted “guarding” that would break if you leaned on it.
In a T-slot system, the connections are the weak points. They use primitive hinges and crudely engineered brackets with minimal ability to support an enclosure or shielding over time.
Any bracket that rotates out of alignment becomes a looser connection. Like a scissor jack lifting a car, overhead pieces on a machine might stay in place when static. But as soon as someone opens an enclosure door or bumps it with a forklift, you’re in trouble.
In a dynamic environment, little movements add up quickly.
Every operator and material handler knows sharp edges are more dangerous than rounded ones. But we’re not talking about cuts and scrapes.
An 80/20 or Bosch aluminum machine frame profile probably won’t slice your arm open, but it may invite a silent killer into your shop – fatigue.
An edge with a severe radius puts more stress on the profiles and can lead to hairline fractures and premature failure. This usually goes unnoticed until it’s too late – and a profile suddenly kicks the bucket.
T-slot modular machine enclosures include a much higher number of components – typically cross-bracing and brackets – to achieve the same results as welded steel. This messy extra framing makes operation and maintenance more dangerous, while undercutting the strength-weight ratio advantages of aluminum.
Self-aligning aluminum structural systems work around this problem by turning connections into a strong point. Because their connecting components form a mechanical lock, they don’t need backup in the form of extra brackets or cross-members. Fewer parts means better visibility and accessibility.
During operation and maintenance, steel and T-slots are paradoxes of industrial machine safety – both half-right, neither the ideal answer. Don’t follow the advice of this section without also taking #4 to heart …
A lot of buyer-supplier discussion lately has revolved around steel-versus-aluminum comparisons. This is true for not just guarding, but machine base frame design as well.
Structural steel has proved to be a formidable option so far, but here’s where it creates an unnecessary headache (and backache).
Think about the assembly and maintenance efforts that go into a high-performance, high-vibration application. Every time a worker has to move a heavy enclosure, it’s added strain that can lead to:
Since metal extrusions use aluminum, they’re about ⅓ the weight of steel. The problem is, even though raw aluminum has an overall strength-weight ratio better than steel, standard T-slot systems lose tensile strength through inefficient engineering.
Self-aligning framing is also aluminum and therefore lightweight, but you don’t need to bulk the system up to match the strength of steel.
Steel rusts. Everyone knows that. Even when painted, it’ll gradually break down in a harsh environment (chemicals, moisture, etc.)
Corrosion is ugly, but it’s more than just an eyesore.
Many bridges on the interstate look safe, but they’re rusting apart below surface level. The same is true with any steel-framed factory machine that’s not well-maintained.
Beyond the gradual loss of stability, there are other safety concerns when workers interact with a corroding structure. Rusted steel flakes are sharp. Contact with one might not only send an employee to the first aid kit, but also to the doctor for a tetanus shot.
If that weren't enough, corrosion also puts particles of metal into the atmosphere, which can contaminate breathing air and hamper machine functionality. In cleanrooms, medical applications, and other areas with sensitive machines, this can cause a safety or quality issue.
To understand the impacts of high temperatures on machine guarding, think about a “shuttle” that removes parts from a heat treatment furnace.
Steel is a highly dense material. This quality has positive implications for durability, but also means steel profiles hold onto heat longer.
Aluminum dissipates heat much faster, decreasing the potential for burns. This is why car radiators are made of aluminum.
Steel has a much higher tolerance for heat without risking structural failure. But any application above 200 °F probably isn’t a place humans will enter or stand next to, so heat-related structural risk is rarely an issue.
If you want to find some budget dollars at your company, don’t just talk to the decision makers about efficiency – talk about safety too.
Your machines might have the same basic components, but they may have totally different safeguarding needs based on their function, build, and operator involvement. Think about the risk level of each application. Then, weigh whether a basic solution (T-slots) will truly suffice … or if an advanced machine frame (steel or self-aligning aluminum) offers better lifetime value.
By protecting your machines, you’ll also protect your team, your operation, and your brand.