MAXIMIZING THE HOLD-DOWN PERFORMANCE OF CNC ROUTERS

Everyone is told to use gasketing under their spoilboard in order to prevent vacuum loss.  but our customers are not in business to hold spoilboards.  THey are in business to hold their parts.  all star helps them do that.

When it comes to holding parts on a CNC Router with vacuum, we are ultimately dealing with a PASS /  FAIL test, right?  Were we able to hold the part, Yes or No.  If the answer is "Yes, we were able to hold that part", that is how it is supposed to run and keep up the good work!!   But when part movement is a problem, there is one reason.  That is because the vacuum system was not sufficient enough.   Too many times, operators who find that their vacuum systems are not sufficient enough to hold parts assume that is the end of it.  They start trying tricks like tab cutting, leaving onion skins behind, or slowing down feed rates.  But there is a way to greatly increase a vacuum's effectiveness and efficiency: proper gasketing material to create an air-tight seal.

Gasketing acts as a compressible, closed-cell sealant that fills the small gap that exists between two solid surfaces.  This microscopic void between the bottom of the spoilboard and the top of the table, if not properly sealed, causes vacuum pressure loss when trying to utilize vacuum hold.  But when gasketed properly, an air-tight, contained area is formed that the vacuum system pulls the atmosphere from.  We are looking to create true VACUUM.  As in the Latin form, vaccus, meaing void of everything.  If we can create a true air-tight vacuum system  (which is physically impossible to achieve on the planet Earth), we could vacuum clamp a grain of rice.  But the reality is vacuum pressure loss is occurring everywhere, but the more we can prevent the more successful we will be in holding our parts.

Slowly and steadily over the past few decades, not only has the number of companies employing CNC routers continue to rise, but so too has the number of companies manufacturing and supplying CNC Routers.  During this this time, a major oversight has been built into the industry that is preventing users the opportunity to achieve maximum performance from their CNC Routers.  The CNC manufacturers will instruct their customers, the old ones, the new ones and the potential ones, to gasket their routers.  To make sure to get a good seal around the table.   To prevent vacuum loss under the spoilboard.   Their job is to make sure that their table is properly vacuum sealed, and the reason a new CNC router usually shows up day one with gasketing in the table: to properly seal the spoilboard.  But we have found companies do not buy routers to hold spoilboards.  They buy routers to hold their parts.  And a company that instructs its customers to vacuum seal a spoilboard but fails to instruct that same customer how to vacuum seal for parts is not providing that customer with a complete understanding of their vacuum system’s capabilities.

The amount of variables that a particular CNC Router operator is dealing with makes it impossible for a one-size-fits-all gasketing solution.  These types of factors can include things like type of router or vacuum is being utilized, the different types of materials being routed, the size of the parts plays a large roll.   Even factors such as why the account at sea level may have more success than his counterpart doing the exact same thing, but in elevated mountain air.  All are important to consider when looking for the best gasketing solution.  But the most important question we need to address: Are we making a lot of a particular part(s) in some type of mass-product environment?   Or are we doing short runs with a lot of turnover?  Because if the answer is short runs, we consider on-board gasketing or nested base tile gasketing to assist a spoilboard environment.   They are quick, easy, inexpensive and extremely effective in holding parts.  If the answer is production parts, the best solution is a dedicated fixture using either In Board Gasketing or Cover Gasketing

 

 

 

GRID GASKETING

Every CNC Router that is employing vacuum hold-down methods needs to incorporate some type of gasketing material.  Most operators are familiar with the gasketing material that is placed in the outer most channel of their CNC router table.  Many CNC Router training seminars will mention: “make sure to get some gasketing material to get good seal around your spoilboards”.  This gasketing material is essential to fill the void between the router table and the spoilboard, creating a quality vacuum clamp on the spoilboards.  We call this Grid Gasketing, and all new and potential users of CNC routers are taught that their machines vacuum performance is dependent on this seal.

The ideal product will fill the channel width-wise evenly and stick above the surface of the channel by roughly 1/16”. Also, a rounded channel should be fitted with a round gasket. Squared channels should be fitted with squared gasketing products. All Star CNC has a Grid Gasket product for each CNC Router Manufacturer. The proper Grid Gasketing product for a particular channel size is crucial to maximizing vacuum performance.  Too narrow and it will slip in the channel.  Too wide and it will pinch when trying to zero out on the z-depth.

IN BOARD GASKETING

When routing repetitive parts, best solution may very well be to make a dedicated vacuum fixture.  When using a non-porous fixture material, a vacuum source can be created for each piece, reducing vacuum loss.  Using a non-porous fixture board also greatly reduces the vacuum loss that would occur through the sides and exposed tool paths of a porous board, like MDF.  An adhesive backing keeps the gasketing material in the pre-routed channels.

 

In-Board Gasketing is intended for long-term use applications.  We call these dedicated fixtures as opposed to spoilboards.  In-Board Gasketing is longer lasting than surface mounted gasketing because it is recessed into the fixture.  When the vacuum is engaged, the gasketing can only compress down the the height of the fixture.  We recommend a 3-to-1 ration in terms of how much sticking above the fixture surface.

ON BOARD GASKETING

When looking for the quickest and most cost effective way to create a vacuum clamp, the ideal solution is On-Board Gasketing.  It is the easiest way to improve a vacuum hold down application on an MDF spoilboard vs downdraft hold only, and frankly it is not even a fair fight.  When introducing gasketing, it changes the hold down environment from a simple downdraft system to a vacuum clamping, suction-cup style system.  It is a different science.  The vacuum clamp hold that is achieved with gasketing is 20X the vacuum pressure of a simple down-draft system.  A simple flick of a finger can move a part on a MDF spoilboard, while a rubber mallet may not move a part out of place that is properly gasketed.On-board gasketing masking

COVER GASKETING

Cover Gasketing products are for small and/or narrow parts that would be difficult to gasket if using one of the other methods because of the limited surface area of the part. By covering the entire fixture with gasketing, users can route parts directly into the gasketing, and then create custom vacuum pocket areas to match the size and shape of their parts.

Cover Gasket can be supplied in pre-sized sheets or custom widths in all thicknesses and densities.

TILE GASKETING

For many of our Nested Base Manufacturing customers, and others doing short-run and custom parts, these Tile Gasketing products present a fantastic option.  These tiles will cover an entire porous MDF surface, creating thousands of mini suction cups to hold parts.  When customers are doing Nested Base Manufacturing, but want to the benefit of vacuum clamping, these tiles are the solution.   Not only will they create vacuum clamps to hold the sheets, but it prevents vacuum leak from occurring through the channels of an exposed spoilboard.  An improved vacuum hold-down system in an ever-changing job environment is why the users of this item make it a part of their Nested Base Manufacturing process.  The product, just like all of the gasketing products, can vary in both thickness and density, to fit each customer’s unique set of variables.  Not all users are attempting to hold the same substrates.

   

 

Learn more about our gasket products when you contact our company to place an order. We can help you get exactly what your business needs. Located in Grass Valley, CA, we can ship products to clients around the world.