When it comes to broad capability, there are a few clear machine tool choices that production units and shops consider most – Five-axis, Vertical and Horizontal Machining Centers. The criterion for choosing looks different depending on what seat you sit in – from ownership to management to purchasing and finance – but from the shop floor perspective it’s all about making chips.

Getting the most out of these highly sophisticated machines involves a combination of processes, programming, tooling, workholding and human creativity. Set up between them is very different, too. Workholding on a 5-axis and Vertical Machining Centers is very straight forward – literally – since the spindle points directly to the table.

Setting up a Horizontal Machining Center (HMC) requires quite a bit more thought because the spindle points to . . . well nothing, just into the open space within the machining envelope. So, what’s the call for it?

Over the years, HMCs have evolved from single station to double, with the use of pallet changers, to pool pallets for multiple setups, and now to even include hydraulics within the pallet to load and clamp on the machine. And the evolution continues.

Today’s HMCs have great productivity characteristics including the ability to continue machining in one location while part change can take place in another. Many feature automatic tool changers and automatic pallet changers making them well-suited for uninterrupted, unmanned and continuous machining.

Configurations with multi-axis spindles also permit true five axis machining. And thanks to gravity, the chips naturally fall away from the parts.

​To meet this great potential, requires a review of several workholding issues at the outset.

1.  Angle Plate or Tombstone
First, let’s get back to the open-air orientation. All machining on an HMC starts with a workholding solution. That’s either going to be an angle plate or tombstone (column) that mounts to the HMC indexing table to provide the position and orientation of the workpiece to the spindle. The choice of this fundamental base is dependent upon the answers to remaining things to consider.

2. The Four Basics
As with all machining, all fundamental requirements must be met. Workpieces must be held securely. They must be positioned to allow access to machine all sides (ideally without having to change). Operations have to be repeatable (within tolerance). And the setup has to be designed to be easy for the operator. That includes the ability to clear chips, load, move and other ergonomic factors with the safety of that individual always being priority one.

3. What is your current need?
If you’re gearing up for the next run of parts, it’s best to begin with an SOW (Scope Of Work) including everything from what you’re looking to accomplish now, to opportunities for greater productivity, and how to best support operator skill level.

4. What is down the road?
On the heels of that, savvy engineers are mindful of future needs. Plan for it now and be ready when the demand arises. This past-the-horizon approach saves time for further utilizing technology such as incorporating robotics and other automation.

5. Opportunities for increased productivity
There are two additional productivity boosters available depending on the application. The first is the move from an angle plate to a tooling column for the ability to load a greater number of workpieces for any given setup. This is just a matter of math – a two-sided column essentially doubles that number, three-sided triples, and four-sided quadruples.

For every incremental increase, there is a corresponding decrease in overall setup time (or downtime), and conversely an increase in productivity (or uptime).

​Connections are standard T-slots or grid patterns. The second opportunity is the addition of a quick-change system that allows the entire column to be removed, changed and the next one connected, fully loaded and all in a matter of minutes or even seconds. This quick on and off works when repeatability is high and avoids having to again find zero for every changeover.

Finding the sweet spot for your shop’s productivity is very much a human effort, and a matter of choosing the best combination of man and machine. In the case of high producers like HMCs, the goal continues to be loading and changing parts faster than the machine can make them.

Charlie Mitchell, machinist for Andretti Autosport, discusses how Unilock pallets reduced his setup time by as much as 80%.

The ER Collet Fixtures provide a simple and low profile solution for clamping cylindrical workpieces using the same technology you are already familiar with in your rotary toolholders.

The anti-lift jaw system from 5th Axis is available for those customers requiring higher precision and accuracy during secondary operation machining.

The system uses a cleat and angled soft jaw to pull the jaw in and down when torque is applied to the lead screw.

Step 1
Loosen shoulder bolts and remove the standard master jaws from the vise base.

Step 2
Take the shoulder bolts and utilize them to bolt the cleats onto the vise base.  Torque shoulder bolts to 20 ft lbs.  (27.11 Nm)

Step 3
Take anti-lift soft jaw and insert the soft jaw into the cleat.  It helps if you insert the soft jaw at a 45 degree angle.  Ensure that soft jaw seats properly into cleat.

Step 4
Take soft jaw covers and place them on the backside of the jaw.  Tighten bolts to secure covers to the soft jaw.  These covers ensure that no chips on debris enter the anti-lift soft jaw.

Clamp confirmation for any system, UNILOCK or otherwise, is a sound design criterion when building any workholding system.

​It is very common to see clamp/un-clamp confirmation in many automated loading systems as safety interlocking of the CNC machine, robot, robot EOA (end-of-arm) tooling, and workholding can all be integrated to a single master control.

Un-clamp confirmation does have a place in manual situations as well, mostly in large part processing, where cranes are used to lift parts off.

When a clamping system is not directly visible underneath a large part, then this requires an external indicator confirming that the system has successfully un-clamped and that it is safe to lift.

The indicators and sensors can be pneumatic switches which are offered by BIG KAISER or electrical proximity switches as offered by many other companies.

We are very excited to announce that we are now able to offer on-site technical training to YOUR machinists at YOUR location!  This is offered at no charge  to customers who use any of the manufacturer's whom we represent in California and Nevada.  

However, just because you don't purchase things from us, don't feel left out! We also offer on-site topic specter training on any of the following topics for $150/hour.  

Each presentation lasts about 2 hours.  The presentations last approximately 45-60 minutes with the remaining time for Q&A and discussion about unique applications in your facility.

Complex part shapes have time consuming part loads to assure the part is properly nested before machining. Blue Photon makes a hard to load part easy and reduces the number of loads.

Traditional workholding does not usually utilize a machine’s full capabilities because of limited machining access therefore multiple workholding fixtures and process steps are required.

*Labor cost per part was calculated @ $50.00 per hour, based on 21 hours run time per (3) 8 hour shifts/5 day work weeks. 6,240 total hrs. per year

Guest Blog
​John Zaya
Product Manager
#Workholding
[email protected]
Tel; 224.770.2930

The concept of using guide pins to load large fixtures has been around for a long time, and it even applies when incorporating Unilock zero-point clamping systems in your fixturing.

The main Unilock clamping knob is very robust, i.e.: very hard, and as such it can cause damage to a Unilock chuck if a fixture is very heavy or large.

Guide pins are set up on the base, and their corresponding holes or notches located on the edge of the fixture pre-position the fixture so, that as it is being lowered, the knobs do not impact the critical location faces of the clamping chuck.

​This also has the added benefit of keeping operators in a safe location not having to use their hands & fingers to fine-adjust a slightly out-of-place fixture being lowered.