Aluminum parts producers are carefully assessing the performance of their extrusion presses as customers such as vehicle component manufacturers, aerospace suppliers, window and door (fenestration) suppliers and other high-volume users seek faster turnarounds and smaller order lot sizes. Customers are also requiring more complex profiles and extrusions with lowered costs.

These industry conditions, along with consolidation among aluminum shapes suppliers, are creating greater operational demands on presses. When parts makers consolidate, they typically move work onto one press and maximize its use, which can strain the machine, particularly an older press.

Extrusion Press Retrofits: Five Factors to Consider

• If your press uses limit-switch or analog controls, greater extrusion velocity accuracy and better butt control is possible with newer digital electrohydraulic controls

• Consider hydraulics efficiency
 and reliability—if your hydraulics platform has servo valves or inline valves, lower cost proportional valves and press control manifolds can be used to simplify system design, reduce leak points and improve pump efficiency

• Energy efficiency can be improved by retrofitting with more efficient hydraulic pumps and motors

• Consider working conditions— safety, environmental hazards from leaking hydraulics, excess noise. A retrofit of aging or inefficient hydraulics and controls can help pay for itself by significantly reducing these costs

• Analyze the “dead cycle” when the press isn’t producing parts. Retrofits can often increase press availability and throughput by up to one part per minute—justifying the investment in new hydraulics or controls.

 

Although some parts producers may feel compelled to completely replace an old extrusion press to keep up with production demands, this major investment may not be necessary. If the press frame is sound, a retrofit and upgrade of key press components, such as hydraulics and controls,
can extend the life of the press and provide a more flexible, reliable and productive long-term solution.

Retrofits offer advantages for long-term value

The cost of a new high-capacity aluminum extrusion press may
cost $2 million or more depending
 on the capacity (plus installation costs); whereas the cost for a typical total retrofit may only be half the
cost of the press.

In retrofits, the hydraulics and controls components and systems are analyzed to identify opportunities where more efficient, latest-generation technologies can improve performance. These include controls such as the latest in proven programmable logic controllers (PLCs) and human machine interfaces (HMIs), closed-loop controllers and hydraulics systems such as the pumping station, valves (including in-line and manifolds) and the interconnected piping.

The benefits of a retrofit include:
• minimal system disruptions 
and downtime,
• longer operational life of major 
(i.e., costly) press components such as the press frame,
• greater throughput, improved troubleshooting and increased parts precision, and
• improved operating conditions and easier maintenance.

Each press operation is unique, and the life and operational performance of a press can greatly vary. Therefore, when considering a hydraulics and controls systems retrofit, evaluate these factors to determine the ultimate scope and return of a press retrofit project.

Factor One: current level of extrusion control

Consider your current level of extrusion control: How precise is
it? What is the scrap rate? How
 much time and effort does it take
 to achieve high-quality, low-defect parts consistently, without added operator intervention? If the output of your press must be scrapped due to unacceptable quality, then it may need better electrohydraulic controls.

Many existing extrusion presses utilize limit switches or analog controls 
to manage hydraulic cycles in the press. These legacy systems could be limiting productivity and adding to waste. Today’s state-of-the-art PLCs and closed-loop pump controllers provide much finer accuracy, whether operators are using press velocity or part temperature to manage extrusion throughput. An improved control system architecture provides greatly enhanced precision and automation of the hydraulics circuit, achieving much higher levels of position, velocity and endpoint control. These controls also allow adjustments during the extrusion cycle to keep production moving. Increased extrusion precision also leads to greater control over but length, helping reduce aluminum waste and increase the number of shapes produced per hour.

This does not mean that you can ignore filtration; filtration is one of the most important elements in helping
 a system to survive for years. In this example, if the pump control valves are not as rugged as they could be,
or require persistent maintenance leading to press downtime, a retrofit incorporating proportional valves may reduce operational costs.

Hydraulic systems also can be simplified (and thus easier to operate and maintain) by replacing inline valve architectures with a single hydraulic manifold. This rationalizes the hydraulic design, reduces the leak points and hydraulic maintenance requirements and also can reduce the number of spare parts that must be stocked to keep the press operating.

Factor Two: hydraulics efficiency and effectiveness

Assess the efficiency and reliability of your hydraulics and controls systems components. You may be using less efficient, more problematic components that are actually reducing productivity. For example, many older-generation presses have servo valves to control the hydraulic pumps and the speed of the press. The servo valves are typically expensive, and require hydraulic fluid that has a dedicated filtration system with finer particulate removal than that of the existing filtration system; if the filter degrades through use, or the filtration systems are not continually maintained, the servo valves clog easily and can disrupt extrusion.

In contrast, the current generation of proportional hydraulic valves can provide the same (and sometimes better) functionality in the hydraulic circuit, yet are much more tolerant of variations in hydraulic fluid quality. This does not mean that you can ignore filtration; filtration is one of the most important elements in helping a system to survive for years. In this example, if the pump control valves are not as rugged as they could be, or require persistent maintenance leading to press downtime, a retrofit incorporating proportional valves may reduce operational costs.

Hydraulic systems also can be simplified (and thus easier to operate and maintain) by replacing inline valve architectures with a single hydraulic manifold. This rationalizes the hydraulic design, reduces the leak points and hydraulic maintenance requirements and also can reduce the number of spare parts that must be stocked to keep the press operating.