All industries, including door manufacturing and assembly, face increased pressures to reduce operator training time, lower labor costs per part, and offer flexibility to meet customer needs anywhere -- and at anytime. Pre-hung door assemblers, for example, have more diverse customer demands than ever before. Whether door orders come from large retailers or niche home builders, the increased need for production speed and accuracy is matched only by the need for versatility and operator ease of use to quickly make changeover adjustments for diverse door styles.

Traditional pre-hung door machines are either versatile or automated, but not both. For automated machines, versatility comes at the cost of slow machine changeover time or a less automated door machine. Versatile machines require time-consuming programming and setup. Norfield Industries, a 40-year-old OEM of pre-hung door machines and systems ranging in production from 50 to 500 doors a day, broke from tradition. Norfield engineers sought a controls and operator interface solution that brought cost-savings and operational benefits to its door-assembly customers.

"We had a vision that required a fundamental change in the way pre-hung door machines operated," according to Chuck Knighten, director of technical development at Norfield Industries. "The ultimate goal was threefold: make machines easier to use for operators, more flexible for various door designs and decrease the cost of ownership."

To reach this goal, Norfield worked with Saber Engineering, Rexel Norcal Valley Electrical Supplies, and Rockwell Automation to apply a new type of control system that integrates servo motion control, a PLC and a touch-screen interface with an intuitive graphical interface. Their collaboration resulted in the Norfield Horizon Type 1 machining center. Norfield's new machining center combines the speed of dedicated automated machines and the versatility of semi-automated machines into one package.

Improved Versatility

For years, pre-hung door machines relied on PLC-controlled pneumatic cylinders for cutting motion. Pre-hung door cutting requirements include bores for the lock, latch and dead bolt, as well as faceplate and hinge mortises on the jambs and door. This creates virtually an unlimited combination of requirements for machining the door.

While the programmable controller proved itself robust enough for harsh manufacturing environments, the pneumatic cylinders had no intelligence to automatically adjust to changing machining needs. They simply retract or extend. When a different door style needed machining, operators had to manually adjust speed, cutters, and travel, taking 15 minutes or more between changeovers.

Norfield searched for an automated solution that would change door machining configurations and bypass the slow, mechanical process of changing cylinder stop positions. With servo motors and drives, Norfield could control cutting speed and position and accommodate changeovers virtually on the fly. Its servo solution came in the form of seven Allen-Bradley 1398 servo drives controlling N-Series servo motors integrated with a state-of-the-art control system.

"During our search for a solution, we knew that a CNC-based system would require extensive operator training, and we believed that PC-based alternatives weren't industrially hardened enough for our customers' facilities," elaborates Knighten.

The brains of the new machining center is the ControlLogix controller. It integrates multi-axis servo control and logic control. A touch screen provides a graphical interface for operator control of the machine. For users, this means changing machining parameters from one door style to another is as easy as pushing a button -- reducing changeover time from 15 minutes or more to, literally, seconds.

Servo control allows the Horizon machine to do an unprecedented variety of cutting positions when compared to existing door machines. Coordinated motion between two servo axes, for example, permits machining of differently sized holes without tool changes. Formerly, this type of interpolated cutting was not available in a robust, integrated PLC package. Servo-controlled machining also saves time with the ability to bore deadbolt and lock holes in one cycle, and further increases flexibility with deep-lock mortise machining. As user machining requirements continue to expand, the Horizon with servo-controlled machining will keep pace.

The Horizon also allows users to easily and intuitively access cutting recipes through the Allen-Bradley PanelView 600T or 1000 operator interface. "User feedback throughout the entire Horizon Type 1 development process kept coming back to one key issue," notes Gary Hubbard, product development engineer at Norfield Industries. "They told us to make the machine easy for operators to use."

No single feature eases operator use more than the integrated recipes. As a blank door and its jamb enter the machining center, the operator simply selects a pre-determined door recipe from the touch screen indicating faceplate and hinge locations and sizes, type of lock, and deadbolt, and any other pre-selected parameters. The command immediately changes cutting tool locations and cutting speeds without the need to make manual changes to pneumatic cylinders and cutting tools, and it does this for various door materials, including wood and steel. This ability to machine different materials -- a growing trend in the industry -- in one machine replaces the need for multiple machines or even production lines, and helps users meet more of their customer's door requirements.

"The nature of our customers' business is challenging," adds Knighten. "They want to run very small lot sizes with a large amount of machining variations because they're meeting the needs of building all the doors, for example, in one house -- from the front door to the closet doors and all the doors in between. Sizes and machining specifications change constantly from door to door, and this machine reduces setup time to seconds."

Users will be able to access a complete library of door recipes directly from the PanelView, completely revolutionizing the concept of setup ease and lowering labor costs per unit in the process.

Remote Service and Support

The machining center is typically the foundation of door pre-hangers' businesses; if it goes down, the entire operation -- from assembly to distribution -- grinds to a standstill. To ensure timely product support and service around the globe, the Horizon system offers a modem connection, which can allow remote diagnostics. Diagnosing the problem and getting a fix -- whether that means a part or expertise -- is critical to getting machines -- and, in many cases, businesses -- up and running.

"Norfield is very service-focused," Knighten explains. "We know that the biggest hurdle to overcoming downtime is to quickly identify exactly what the problem is and exactly what part is needed. Now, we can remotely troubleshoot a machine in Texas, for example, and diagnose the problem without the time and cost associated with a site visit."

From across the world, Norfield is able to identify when a part needs fixing, such as a cutting tool that's become so dull it's starting to stress the motors and affect product quality. In addition, Norfield can remotely make software upgrades so users always operate with the latest, most-efficient version.

It's the Whole Package that Can Make the Difference

Ease of setup for each recipe is just the beginning. With ControlLogix and its networking capabilities, the machining center could potentially become a core element of total system integration. For example, if the users' order-entry software could generate a bar code, the operator could simply scan in the door parameter, further increasing the ease of setup and changeover.

With the ControlLogix networking capability, users could actually enter the orders for a particular application offline from the front office. Since many of Norfield's customers have order entry software (OES) systems, the opportunity exists for them to interface OES systems and create a seamless connection between order entry/inventory systems and scheduling systems directly in the machine. In the future, operators could simply press a menu item -- "Order #53C," for example -- to further ease use and add even more flexibility for the user to switch the order, while providing tighter inventory control.

"With ControlLogix, Norfield is moving further and faster toward creating a total integrated manufacturing process for its customers," comments Barry Wagoner, senior project manager at Saber Engineering. "It's taking the benefits of coordinated multi-axis control for servo motors to a new level in this industry."

A Path to the Future

The seamless combination of servo drives and motors, open control and a graphical interface opens the door to operator ease and application versatility. From small to large shops, Norfield has developed a control solution that offers users throughput-enhancing technology that decreases operating costs and provides a lower long-term cost of ownership. In addition to improving processes for Norfield's customers today, the Horizon Type 1 Machining Center is positioned as the foundation for forward migration to plant-wide system integration.