Most vacuum workholding systems lock you into one approach. VFS lets you pick the strategy that fits the job. Here is how each one works and when to use it.
How Vacuum Workholding Works with VFS
One plate. Four sealing strategies. Your choice.
The Four Sealing Strategies Same plate, four ways to seal.
Pick the strategy that fits your job. The plate handles all of it.
Dry Machining
Wet Machining
One-Off
Prototyping
Vacu-Card
Sheet material self-seals to the part. Setup in under a minute.
Source from Datron
Cord Gasket
Custom perimeter around the part 2 to 5 minutes to lay.
Source from McMaster-Carr
Dedicated
Production
Sub-Plate
Dedicated fixture bolted on top. Instant set up once built.
Build your own or talk to us
Sub-Plate
Same approach, sealed for flood. Handles complex geometries.
Build your own or talk to us
Hybrid setups combine vacuum with mechanical fixturing.
Lay a sheet of Datron Vacu-Card on the plate. Set the part directly on top. Pull vacuum. The card compresses under atmospheric pressure and seals itself to both the plate and the part. The part is held flat and immobile across its entire bottom surface.
Best for: Datron machines and high-speed router-style platforms running dry or with minimum quantity lubrication (MQL, atomized ethanol or oil). Vacu-Card holds well in those workflows because there is no flood coolant to disrupt the seal. Also a fast setup choice for prototype and one-off work where cutting a custom gasket groove is overkill.
Setup time: under a minute once Vacu-Card is cut to size.
Small part rule: standard Vacu-Card holds best when the part covers at least two grid zones (about 200mm x 100mm). For parts smaller than that, use Datron’s VacuCard+ (the adhesive-layer version) which adds enough holding force to keep small parts in place.
Where to source Vacu-Card and VacuCard+: directly from Datron. VacFixture does not resell it because you are likely already sourcing from Datron and the logistics do not make sense.
Lay cord gasket in a custom perimeter around the part. The cord compresses under atmospheric pressure and seals against both the plate and the bottom of the part, creating a defined zone where vacuum pulls. Outside the cord, the plate is sealed off. Coolant doesn’t reach the vacuum system.
Best for: standard vertical machining centers running flood coolant. Haas, Brother, Doosan, Fanuc Robodrill, Hurco, and the rest of the wet-machining VMC family. The defined sealing zone keeps coolant out of the vacuum system, and the cord works under flood conditions where Vacu-Card would not.
Setup time: two to five minutes to lay a custom perimeter.
Where to source cord gasket: McMaster-Carr part number 8605K115 (EPDM foam cord, 1/8 inch diameter). This is the same material we recommend in our manuals. Cut a groove .118 inch wide by .100 inch deep with a .015 inch chamfer at the top. Standard, cheap, always in stock. VacFixture does not resell it.
Critical rule: when using cord gasket, never machine through the bottom of the part. Breaking through the bottom creates a leak the vacuum cannot keep up with, and the part will release from the plate (potentially at speed). Plan your toolpath accordingly.
The VFS plate ships with threaded conical inserts on a 50mm grid. Standard threading is M6 (M8 optional). These threaded conicals are the integration point for any sub-plate or fixture plate you build on top of the VFS. Design your fixture with the same 50mm grid, drop it onto the VFS, bolt through the conicals, and you have a custom workholding solution that integrates with the vacuum surface underneath.
Three common ways to use sub-plates:
Removable prototyping fixtures. Build a sub-plate with a pocket that matches a specific part geometry. Bolt it on when you run that job, pull it off when you don’t. Faster to swap than rebuilding a vacuum sealing zone every time. Good for shops that run a regular rotation of jobs.
Dedicated production sub-plates. Machine a sub-plate for a recurring part and leave it on the base plate for the production run. The sub-plate defines the sealing zone and part locator in one piece of hardware. Setup is instant after the first one. Good for repeat work.
Hybrid vacuum and fixture setups. The most underused option. Use vacuum to hold one portion of an assembly and mechanical fixturing (stop blocks, clamps, locators) on another. Useful when one half of the part has a flat sealable surface and the other half needs positive mechanical retention. Lets you run jobs that neither pure vacuum nor pure fixturing can handle alone.
Setup time: depends on the use. Prototyping sub-plates swap in seconds once built. Production sub-plates are instant. Hybrid setups take as long as the mechanical side does.
Where to source: build your own using the threaded conicals as the integration foundation, or talk to an engineer and we’ll build one for you.
Individual rubber plugs close off specific vacuum ports in the plate. Works alongside all three sealing strategies above. Use plugs to concentrate vacuum on the sealed area when the part is smaller than the plate, preventing vacuum loss through unused ports.
Best for: small parts on big plates, multi-part fixturing where zones need different vacuum levels, maximizing hold force when pump capacity is the limiting factor.
Setup time: seconds.
Where to source: VacFixture. Plug packs are a standalone accessory SKU.
Vacuum Workholding Limits and Sizing Rules of Thumb Practical limits worth knowing before you cut.
Minimum part size
For standard cuts, the smallest part you should hold on a VFS plate is two grid zones (approximately 100mm x 200mm). Smaller than that and the sealed area shrinks below what the vacuum can hold reliably.
For aggressive cuts (heavy material removal, big tool engagement), the recommended minimum doubles to four grid zones (approximately 200mm x 200mm). The bigger the sealed area, the more clamping force atmospheric pressure delivers, and the more aggressive you can cut without lift.
Smaller parts can still work in a few cases: a sub-plate with a pocketed locator, VacuCard+ (Datron’s adhesive-layer version) for dry work, or plugs to concentrate vacuum on a smaller sealed zone. If your part is below the minimums and these workarounds do not fit, vacuum is probably the wrong workholding for that job.
Tool diameter and engagement
8mm is a comfortable upper limit for side milling and pocketing on a vacuum-held part with conventional toolpaths. Below 8mm, cutting forces stay low enough that the part stays put through normal step-overs and feeds.
You can run larger tools, including face mills, when the strategy is right. Above 8mm the side pressure on the part increases, so engagement and aspect ratio matter more than tool diameter alone. High-speed milling with a long aspect ratio of flute and very light radial engagement keeps cutting forces manageable and is a safer approach with bigger tools. The general rule: if your toolpath strategy keeps cutting forces low and uses adequate sealed surface area to back it up, larger tools work. If you are pushing aggressive engagement on a small part, stay under 8mm.
Facing is its own case. You can face with larger tools without much risk because the cut is shallow and the part is supported across its full bottom surface.
Toolpath strategy
Climb milling beats conventional milling on vacuum. Light radial step-overs beat heavy ones. High-speed milling techniques (long aspect ratio, light engagement, fast feed) work well with the system. If you find yourself wanting to push parameters above what feels right for vacuum, consider whether the part should be in a vise or a sub-plate instead.
Which Vacuum Workholding Strategy for Which Job A quick decision guide.
Start with Vacu-Card. It’s the fastest setup and works for most dry machining.
Cord gasket. Vacu-Card doesn’t hold up under flood. The cord defines the sealing zone and keeps coolant out of the vacuum system.
Build removable sub-plates for the parts you run often. Swap them in and out as the job changes. Faster than rebuilding a sealing zone every time.
Dedicated sub-plate. One-time investment to machine it. After that, every setup is instant. The plate becomes dedicated production hardware.
Hybrid setup. Vacuum holds the flat zone, mechanical fixturing handles the complex side. Build a sub-plate that combines both into one fixture.
Use plugs to close off unused ports, regardless of which sealing strategy you’re using. Gets you more hold force and faster pump-down.
Vacuum Supply Notes
What pulls the vacuum
All four strategies work with any vacuum source that pulls 20 inches of mercury or better. The VacFixture venturi kit uses a Festo VN-30-H generator. At 3 bar input pressure it produces up to 93 percent vacuum (0.93 bar) and 186 liters per minute of flow. Nominal operating pressure is 6 bar. The kit mounts magnetically to the outside of your machine enclosure.
A dedicated vacuum pump is an option if you already have one. For plates over 500x700mm or tiled configurations, a large pump or multiple venturi kits (one per plate) is recommended for adequate pump-down. Datron users can plumb directly into the machine’s built-in vacuum, no external supply needed.
How to Face a Vacuum Fixture Plate In-Situ
One workflow step before you run your first job
Every VFS plate ships un-faced. The upper plate is machined parallel within 0.1mm during manufacturing, but the working surface needs to be faced in-situ on your machine to match your machine’s level exactly. This is a one-time process and takes about an hour.
The basic process: import the .step file from the product page into your CAM, set X and Y origin to the indicated locating bore with Z origin at the top of the plate, program a facing pass 0.05mm below the top surface, install one of the included conical locators in the WCS bore and probe it for X/Y plus the plate top for Z, remove the conical, then run the program. Continue facing in 0.01mm increments until the entire working surface cleans up. Once faced, the plate is yours: it can be removed from the machine and reinstalled later without refacing.
Full step-by-step instructions ship with every plate and are available on each product page. If you want a walkthrough before your first run, talk to an engineer.
Two articles worth your time
These two pieces go deeper than what fits on this page. Written by our team for shops getting into vacuum workholding for the first time and shops looking to get more out of what they already run.
Still Have Questions?
The fast path is a phone call
Every shop’s setup is slightly different, and the right sealing strategy depends on the specific job. If you want a 10-minute conversation to figure out what fits your work, talk to an engineer.
Vacuum Workholding FAQs
Quick answers to common questions about vacuum workholding setups, sealing methods, and when to use each strategy.
Use Vacu-Card for dry machining. It is the fastest setup and works well when there is no flood coolant. Use cord gasket for wet machining. The gasket defines a sealed zone and keeps coolant out of the vacuum system.
If you are running flood coolant, use gasket. If you are running dry or MQL, start with Vacu-Card.
Dry vacuum machining uses no flood coolant, which allows materials like Vacu-Card to seal directly between the part and the plate. Wet machining uses flood coolant, which breaks that seal. In these cases, a cord gasket is used to isolate the vacuum zone and keep coolant out. The sealing method changes based on the presence of coolant, not the machine itself.
Use a sub-plate when the same part runs repeatedly or when the geometry is too complex for a simple sealing perimeter. A sub-plate defines both the sealing zone and part location in one piece of hardware. It reduces setup time and improves repeatability compared to rebuilding a gasket or reseating Vacu-Card for each run.
Yes. Vacuum can hold flat surfaces while mechanical fixturing secures features that require positive retention.
These hybrid setups are used when a part cannot be fully held by vacuum alone. The combination allows more flexibility than either method on its own.