Single Vise vs. Multi-Vise Setup: How to Maximize Parts Per Cycle on Your CNC Machine Table

There is a number that every CNC shop manager watches more closely than any other: spindle utilisation. It is the percentage of paid machine time during which the spindle is actually cutting metal. In most production environments, that number is lower than it should be — and a significant portion of the gap is caused not by programming, tooling, or material, but by workholding strategy.

A machine running a single vise, holding one part per cycle, is a machine that stops every time a part is finished. The operator unclamps, removes the finished part, loads a new blank, clamps, re-zeros if necessary, and restarts the program. On a 4-minute cycle, a 90-second load/unload sequence represents a 37% reduction in effective spindle time — before accounting for any setup changes between jobs.

The solution is not always to buy a faster machine. It is often to change how the existing machine's table is used.

This article covers the four primary workholding configurations available to CNC shops — single vise, multi-vise side-by-side, dual-station, and high-density — with the cycle time mathematics behind each, the table layout logic, and the specific Zhenghao products that enable each configuration.

Why Workholding Layout Is a Productivity Decision, Not Just a Setup Decision

Most shops treat workholding as a setup problem: find a vise that holds the part, bolt it to the table, run the job. This approach works. It just does not work efficiently.

The more productive approach treats workholding layout as a production engineering decision — one that is made before the first part is cut and that directly determines the output rate of the machine for the entire production run.

The variables that workholding layout controls:

• Parts per cycle — how many finished parts come off the machine each time the program completes

• Load/unload time as a percentage of cycle time — the lower this ratio, the higher the effective spindle utilisation

• Setup time between jobs — how long the machine sits idle when switching from one part number to another

• Table qualification time — how long it takes to verify that all vises are correctly positioned and co-planar after a setup change

Each of these variables has a direct cost. And each can be reduced — often dramatically — by selecting the right workholding configuration and the right vise products.

Configuration 1: Single Vise, Single Part Per Cycle

The baseline configuration. One vise, one part, one cycle.

When it is the correct choice

Single-vise setups are appropriate when:

• The workpiece is large — close to the maximum jaw width of the largest available vise

• The machining operation requires access to five or six faces of the part, demanding maximum clearance around the workpiece

• The part is a prototype or first article where only one or two pieces are needed

• The workpiece requires complex custom soft jaws that are not practical to duplicate across multiple vises

For large mould blocks, large aerospace structural components, or one-off prototype work, a single GT300 Series vise is often the correct and only practical choice. The GT300's 12,000 N clamping force and 300 mm jaw width provide the clamping security needed for heavy roughing on large workpieces.

The productivity ceiling of single-vise setups

For any part that is smaller than the machine table and produced in quantities greater than a handful, the single-vise configuration imposes a hard ceiling on productivity. The cycle time structure looks like this:

$$T_{total} = T_{cut} + T_{load/unload}$$

Where $$T_{load/unload}$$ is fixed regardless of how fast the machine cuts. If $$T_{cut}$$ is reduced by better tooling or higher feeds, the load/unload time becomes a larger fraction of the total — and the productivity gain from the tooling investment is partially absorbed by the fixed overhead of single-part loading.

Example:

• Cutting time per part: 5 minutes

• Load/unload time: 1.5 minutes

• Effective cycle time: 6.5 minutes

• Parts per hour: 9.2

• Spindle utilisation: 77%

This is the baseline against which multi-vise configurations are measured.

Configuration 2: Multi-Vise Side-by-Side — The Modular Advantage

The most straightforward productivity upgrade: mount multiple vises on the machine table and run a multi-part program that machines all parts in a single cycle.

How it works

Two, three, four, or more vises are mounted side by side along the X-axis of the machine table. Each vise holds one part. The CNC program is written (or mirrored/offset) to machine all parts in sequence within a single program execution. The operator loads and unloads all parts between cycles — but the load/unload sequence happens once per cycle regardless of how many parts are in the setup.

The productivity mathematics change fundamentally:

$$T_{total} = T_{cut} \times N_{vises} + T_{load/unload}$$

Where $$N_{vises}$$ is the number of vises (and parts) in the setup, and $$T_{load/unload}$$ is now spread across all parts in the cycle.

Example with 3 vises side by side:

• Cutting time per part: 5 minutes

• Total cutting time for 3 parts: 15 minutes

• Load/unload time (all 3 parts): 3 minutes (1 min per part, done simultaneously)

• Effective cycle time: 18 minutes

• Parts per hour: 10 parts (3 parts per 18-minute cycle)

• Spindle utilisation: 83%

• Productivity gain vs. single vise: +8.7% parts per hour, +6% spindle utilisation

But the real gain is in the load/unload ratio. With 3 vises, the operator loads 3 parts in approximately the same time it takes to load 1 — because the vises are adjacent and the motion economy of loading multiple parts in one standing position is efficient. The fixed overhead of walking to the machine, opening the guard, and restarting the program is shared across all 3 parts.

The GT Series modular design enables this directly

The GT Series vise body is precision-ground on all six faces to 0.005 mm squareness and parallelism. This is not just a precision specification — it is what makes multi-vise side-by-side setups practical without individual vise qualification.

When multiple GT Series vises are mounted on the same T-slot row, they sit co-planar and co-height without shimming. The machine does not need to probe each vise individually to establish its Z-height and orientation. The vises are, by design, interchangeable references.

This is the difference between a precision-ground modular vise and a conventional machine vise. A conventional vise may be accurate in isolation, but mounting three of them side by side and expecting them to be co-planar to within 0.01 mm without individual qualification is not realistic. With GT Series vises, it is the expected result.

Table layout for multi-vise setups

3 × GT100 side by side on a 400 mm VMC:

|←  100 mm  →|←  100 mm  →|←  100 mm  →|
[ GT100 #1  ][ GT100 #2  ][ GT100 #3  ]
|←————————— 300 mm total jaw width ————————→|
|←————————— 270 mm vise length (Y-axis) ——→|

Combined footprint: 300 mm (X) × 270 mm (Y). Fits a standard 400 × 400 mm VMC table with clearance. Three parts per cycle.

2 × GT150A side by side on a 400 mm VMC:

|←——— 150 mm ———→|←——— 150 mm ———→|
[   GT150A #1   ][   GT150A #2   ]
|←—— 300 mm total jaw width ——→|
|←—— 420 mm vise length (Y) ——→|

Combined footprint: 300 mm (X) × 420 mm (Y). Two parts per cycle, each up to 120 mm wide.

4 × GT125 side by side on a 600 mm HMC:

|← 125 →|← 125 →|← 125 →|← 125 →|
[GT125#1][GT125#2][GT125#3][GT125#4]
|←——— 500 mm total jaw width ———→|
|←——— 345 mm vise length (Y) ———→|

Four parts per cycle. Particularly effective on horizontal machining centres where the pallet can be indexed to machine additional faces without unclamping.

Quick-change jaws: the multi-vise setup multiplier

In a multi-vise side-by-side configuration, jaw changes between jobs multiply: changing jaws on 4 vises takes 4× as long as changing jaws on 1 vise. This is where the GT Quick-Change Jaw System delivers its most significant productivity advantage.

With conventional bolted jaws, changing jaw types on 4 vises requires removing and replacing 8 pairs of jaw bolts — a 20–30 minute operation. With the GT Quick-Change Jaw System, all 4 vises can have their jaws swapped in under 5 minutes. The jaw-change time overhead of running a multi-vise configuration is effectively eliminated.

Configuration 3: Dual-Station Vise — Two Parts, One Footprint

The dual-station approach achieves two parts per cycle from a single vise footprint — without requiring additional T-slot space or a second vise qualification.

How the ZQ83 Double Action Vise works

The ZQ83 Double Action Precision Vise features a fixed central jaw flanked by two independent movable outer jaws. When the lead screw is turned, both outer jaws move inward simultaneously, clamping two workpieces against the rigid central jaw in a single operation.

The result: two parts clamped, two parts machined, two parts unclamped — with the same single lead screw operation that a standard single-station vise uses for one part.

Productivity mathematics: ZQ83 vs. single vise

Single vise baseline:

• Cutting time: 5 min/part

• Load/unload: 1.5 min/part

• Cycle time: 6.5 min

• Parts per hour: 9.2

ZQ83 dual-station:

• Cutting time: 5 min/part × 2 parts = 10 min cutting

• Load/unload: 2 min (both parts, single clamping operation)

• Cycle time: 12 min

• Parts per hour: 10 parts (2 parts per 12-min cycle)

• Productivity gain: +8.7% parts per hour

But the more significant gain is in operator efficiency. The operator performs one clamping operation to load two parts — the physical effort and time of a single clamp, with the output of two. Over a full shift, this reduces operator fatigue and frees attention for other tasks.

When the ZQ83 is the better choice than two separate vises

The ZQ83 is particularly effective when the machine table is already occupied by other fixtures and there is only one available T-slot position — or when the workpiece size is well-matched to the dual-station jaw geometry.

Configuration 4: High-Density Multilex Vise — Maximum Parts Per Square Metre

For the highest-volume production scenarios — where the goal is to maximise the number of parts on the table in every possible cycle — the ZH Series High-Density Multilex Vise represents the upper end of the workholding density spectrum.

The Multilex concept

The Multilex (multi-clamping) vise design extends the dual-station concept further: a single vise body with multiple clamping stations arranged along its length, each capable of holding an independent workpiece. The result is a workholding unit that occupies a defined table footprint and delivers the maximum number of clamped parts within that footprint.

For small-to-medium precision components — the type produced in high volumes in automotive, medical device, and electronics manufacturing — the Multilex configuration can place 4, 6, or 8 parts on a single vise unit, all clamped in a single or dual lead screw operation.

Comparing configurations by parts per table area

The Multilex configuration delivers the highest parts-per-cycle density — but it is optimised for a specific workpiece size range and is most cost-effective when the production volume justifies the dedicated setup.

The Hidden Cost: Setup Time and Table Qualification

Parts per cycle is only one half of the productivity equation. The other half is how long the machine sits idle between jobs.

In a job shop or mixed-production environment, the machine switches between part numbers regularly. Each switch requires:

1. Removing the current vise setup

2. Mounting the new vise setup

3. Qualifying the new setup (probing vise faces, setting work offsets)

4. Running a first article to verify the setup

For a single vise, this process might take 20–30 minutes. For a multi-vise side-by-side setup with conventional vises, it can take 45–90 minutes — because each vise must be individually qualified.

How the GT Series reduces qualification time in multi-vise setups

Because all GT Series vises are precision-ground to the same 0.005 mm standard on all six faces, a multi-vise setup using GT Series vises can be qualified as a single unit rather than as individual vises. The operator probes one reference point on the first vise, applies the known inter-vise spacing as an offset, and the remaining vises' positions are calculated — not measured individually.

This reduces the qualification time for a 3-vise side-by-side setup from approximately 45 minutes (individual qualification) to approximately 10–15 minutes (single-reference qualification with offset calculation).

How the Quick-Change Jaw System reduces job changeover time

When the vise bodies remain on the table between jobs and only the jaw types change, the GT Quick-Change Jaw System eliminates the jaw-change component of setup time entirely. The vise bodies stay bolted to the table — maintaining their qualified positions — and only the jaw inserts are swapped. No re-qualification is needed because the vise body position has not changed.

For a shop running 3–4 different part families on the same machine, this approach can reduce job changeover time from 60+ minutes to under 15 minutes.

Choosing the Right Configuration: A Decision Framework

Calculating Your Productivity Gain: A Working Template

Use this template to estimate the productivity gain from upgrading your workholding configuration.

Step 1 — Establish your current baseline:

$$\text{Parts per hour (current)} = \frac{60}{T_{cut} + T_{load/unload}}$$

Step 2 — Calculate the multi-vise scenario:

$$\text{Parts per hour (multi-vise)} = \frac{60 \times N}{T_{cut} \times N + T_{load/unload} \times N \times k}$$

Where:

• $$N$$ = number of vises (parts per cycle)

• $$k$$ = load/unload time efficiency factor (typically 0.6–0.8 for side-by-side loading — loading multiple adjacent parts is faster per part than loading a single part)

Step 3 — Calculate annual output gain:

$$\Delta\text{Parts per year} = (\text{Parts/hr multi-vise} - \text{Parts/hr single}) \times \text{Hours per year}$$

Worked example:

An 11.9% increase in annual output from the same machine, same operator, same cutting parameters — achieved purely by changing the workholding configuration from one vise to three.

Practical Considerations Before Changing Your Setup

Program structure

A multi-vise setup requires a CNC program that machines all parts in the setup. This is typically achieved by:

• Mirroring or offsetting the single-part program by the inter-vise spacing (for identical parts in identical vises)

• Subprogram calls with different work offset numbers (G54, G55, G56...) for each vise position

• Parametric programming where the vise spacing is a variable parameter

Modern CAM software handles multi-vise program generation automatically once the vise layout is defined in the setup sheet.

Coolant coverage

Multiple vises side by side require that the machine's coolant delivery system covers the full X-axis span of the setup. For setups wider than approximately 400 mm, through-spindle coolant or multiple nozzle positions may be needed to ensure adequate coolant reaches all cutting positions.

Chip management

More parts per cycle means more chips per cycle. Ensure the machine's chip conveyor or chip tray can handle the increased chip volume without requiring mid-cycle operator intervention to clear chips.

Tool life management

In a multi-vise setup, each tool cuts more material per cycle. Tool life monitoring becomes more important — a tool that fails mid-cycle in a multi-vise setup scraps multiple parts simultaneously. Consider implementing tool life management in the CNC controller to flag tools approaching end-of-life before they fail.

Summary

The single most underutilised productivity lever in most CNC shops is the machine table itself. A machine running one part per cycle on a table that could hold three is a machine operating at one-third of its potential output — not because of the spindle, the tooling, or the programming, but because of the workholding layout.

The GT Series modular design — precision-ground on all six faces, interchangeable across all jaw types, compatible with quick-change jaw systems — is specifically engineered to make multi-vise configurations practical, fast to set up, and accurate enough for precision production work.

Whether the right configuration for your application is two GT150A vises side by side, a ZQ83 dual-station for limited table space, or a high-density Multilex setup for maximum parts per cycle — the starting point is the same: treat workholding layout as a production engineering decision, not an afterthought.

Explore the full Zhenghao precision vise range at www.pyzhjx.com/product-6-1.html, or contact our technical team to discuss the optimal configuration for your specific machine and workpiece.

Email: zhjx@pyzhjx.com

Phone / WhatsApp: +86-18660185316

FAQ

How many GT Series vises can be mounted side by side on a standard VMC?

The number depends on the machine's X-axis travel and the jaw width of the selected vise. On a 600 mm X-axis VMC: up to 6 × GT100 (100 mm each), 4 × GT125 (125 mm each), or 3 × GT175 (175 mm each). On a 1,000 mm X-axis VMC, the numbers scale proportionally. The GT Series' precision-ground modular body means all vises in the row will be co-planar and co-height without individual shimming.

Does running multiple vises side by side affect machining accuracy?

No — provided the vises are correctly mounted and the program uses the correct work offsets for each vise position. Because all GT Series vises are ground to the same 0.005 mm standard, the positional relationship between vises is consistent and predictable. The inter-vise spacing (jaw width + any gap between vises) is a fixed, measurable dimension that can be entered directly into the CNC controller as a work offset increment.

Can the ZQ83 dual-station vise hold two different-sized workpieces simultaneously?

Yes, within limits. The ZQ83's two outer jaws move simultaneously from a single lead screw, so both workpieces must be clamped at approximately the same jaw opening. If the two workpieces differ significantly in width (more than approximately 10–15 mm), the clamping force distribution between the two stations will be uneven. For best results, the ZQ83 is optimised for two identical or near-identical workpieces. See the ZQ83 Double Action Vise product page for full specification details.

What is the minimum workpiece size for a multi-vise side-by-side setup?

There is no absolute minimum, but workpieces smaller than approximately 30 mm wide become difficult to clamp reliably in a standard GT Series vise jaw. For very small precision components, consider the QGG Series compact toolmaker vises, which are designed for small workpiece clamping and can also be mounted in multi-vise configurations.

How does the Quick-Change Jaw System maintain precision when jaws are swapped between jobs?

The GT Quick-Change Jaw System uses a precision dovetail or wedge-lock interface between the jaw insert and the vise body. This interface is ground to the same 0.005 mm standard as the rest of the vise. When a jaw insert is engaged and locked, it returns to the same position — within the system's 0.003–0.005 mm repeatability — every time. The jaw-change does not affect the vise body's position on the machine table, so no re-qualification of the vise position is required after a jaw swap. Full details at the GT Quick-Change Jaw System product page.