Investing in a five-axis future

UKsub To meet the busy production demands of a Network Rail contract, Lancashire-based Howells Railway Products Ltd has invested in 26 Haas CNC machines, including a pair of five-axis UMC-750 models.
Founded in 1947, Howells Railway Products remains an independent, family-run firm. All engineering and assembly work is carried out under one roof at the company’s facility in Wythenshawe, near Manchester. Howells Railway has recently undergone a major expansion, which was necessary to fulfil the Network Rail contract, as one of its manufacturing partners. The project included the addition of a 40,000 sq ft CNC workshop, sympathetically designed to complement the company’s impressive Art Deco building.
Howells’ new workshop is filled exclusively with Haas CNC technology, including the latest UMC-750 five-axis machines, along with vertical machining centres, mini mills, two-axis and Y-axis turning centres, and toolroom lathes.
David Howells, managing director, explains: “We examined the CNC machine tool market very carefully, and concluded that the Haas machines offered us the best levels of accuracy and dependability, for the right money. After seeing them in action at the showroom, including some astonishing cuts being made by an ST-30 CNC turning centre, we knew Haas were the right machines for us.

“The first batch of machines was installed in late 2013, since when have continuously expanded our capabilities by investing in more Haas equipment, including our most recent purchase of two five-axis machining centres, one in December 2016 and another in May 2017,” he adds.
“With the help of the Haas applications department we’ve tweaked our processes to be as efficient as possible. By changing the order of operations and adjusting certain cycle times we’ve increased machine runtime to its optimum level. One operator can comfortably run three machines; because of the shared Haas control our operators are equally at home on both the mills and lathes.”
Howells Railway clearly has confidence in the Haas control. In fact, the UMC-750 is supplied as standard with everything needed for full five-axis machining, including some essential macros specifically for the dynamic repositioning of parts.
“Where possible we’ll use multiple fixtures,” says Howells. “For example, the steel tube part of our stretcher bar assembly is profiled on one of the TL-3s before being placed in a rotary on the back of the table on one of the VF-4SSs, which is simultaneously used to face and bore the steel forgings that house the motion units.”

Stretcher bars are safety critical components in the design of a set of railway points. They keep the switch rails in the correct position under the passage of a train. A stretcher bar holds the two rails a defined distance apart at all times and ensures that both rails move simultaneously as a coupled pair when commanded.
Any failure of a stretcher bar can, in extreme circumstances, lead to the derailment of a train, as occurred at Potters Bar and Lambrigg. As a result of these incidents, the assembly has been under scrutiny by Network Rail for some time and improved function and reliability was deemed to be of paramount importance.
The tubular stretcher bar is a new design, created by Network Rail as a high-integrity replacement for existing designs on the UK rail network. Effectively a cold drawn steel tube, the bar is connected to a motion unit at either end. Each motion unit contains pre-compressed elastomeric components in a forged steel housing, which is designed to damp the transmission of loads imparted from railway vehicles into the tube.
Stretcher bars have to permit adjustment, so the points can be set up properly and then locked. The new design demands the highest levels of quality and precision, however they are simpler to install, require less maintenance and are designed to withstand the rigours of the 21st century railway.
With its Haas machines, Howells Railway is effectively getting a bonus operation. Travels are very important with these set-ups, which is where the VF-4SS comes into its own. With small work envelopes, machine shops are often limited to performing perhaps just one machining operation at a time, or cutting one side of a part. More travel can help shops become more efficient by allowing multiple fixtures and operations.

“Most of our VF-4SS verticals are equipped with Haas rotaries and are used to cut component parts for the motion units; these need to line up when assembled and precision is crucial,” says Howells. “We’ve found the rotaries to be extremely accurate; within 0.25° over the dozen or so turns in this final operation.
“Apart from the forgings, which we managed to source from a UK company, everything is manufactured in-house,” he continues. “This means we can keep a close eye on quality at every stage. All parts go through numerous safety sign-offs and assembly checks and, similarly to aerospace, there’s a double documentation trail to ensure traceability and compliance.”
The two UMC-750s were not purchased as part of Howells Railways’ original plan for the machine shop refit. However, their value and capability simply proved too good to ignore.
“We decided to go the extra mile and future-proof ourselves,” says Howells. “We are glad that we did; we have worked with a combination of three and four-axis set-ups on the existing VMCs, including multiple four-axis drives on the same machine, but the UMCs gave us fully synchronous five-axis capability.”
Working in five axes has proved invaluable, giving a rapid turnaround for the fixtures used on the company’s new robotic fibre laser welder, along with simplifying some of the longer multiple operation machining on the company’s traditional product lines to single operation. Howells Railways is already planning space to accommodate more Haas machines.
“It’s an exciting time for us,” concludes Howells. “We’ve changed more in the past few years than in the previous 60. As our range of products has become more technologically innovative, so has our approach to their production. Thanks to the Haas machines and the changes we’ve made as a company, we’re doing things quicker, better and more efficiently, while also improving quality.”
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EDM simplification through innovation

Innovative CAM technology can and should simplify the entire programming process. However, working with wire and water, instead of speeds and feeds, presents a challenge for CAM systems originally developed for conventional milling and turning applications. The concept of removing material with a cutter does not translate easily to the concept of eroding material with a thin wire.

Slicing through metal with an energised wire is a very efficient way to cut intricate shapes. These intricate part shapes have physical properties unique to the wire-cutting process, and include constant tapers, variable tapers, vertical land areas, sharp corners, radius corners, sharp corners that taper into radius corners, and more. A first step to simplifying the programming process is for a CAM system to recognise and retain knowledge of those unique properties so that wire programming can be automated.
Esprit is a feature-based CAM system that automatically recognises machinable features that are specific to wire machining. Choices include die (pocket), punch (boss), hole, open profile, and even turning profile features for wire machines equipped with a rotary table.
An emphasis is placed on fast and easy creation of machinable features for wire EDM. Detailed properties about XY and UV profiles, workpiece height, tapers and corner styles are associated with the EDM features so that, regardless of the type or number of operations applied to the feature, the integrity of the underlying data remains the same. When EDM properties are embedded in the feature, the entire programming process is streamlined because most of the data needed for programming is coming from a single, reliable source.
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Wire EDM can replace broaching for fir tree slots

As aerospace OEMs and supply chain companies face increasing pressure to produce more fuel-efficient aircraft, wire EDM (WEDM) is emerging as a key machining technology, reports GF Machining Solutions. According to a body of evidence generated by David Welling at the Laboratory for Machine Tools and Production Engineering (WZL) at RWTH Aachen University (Germany), WEDM has the potential to replace broaching as the technology of choice for the manufacture of fir tree slots for found in high-pressure compressor and turbine disks.

“Broaching tools have obvious limitations; one of these is the high tool wear that results from the increased toughness of aerospace materials,” says Welling. “Also, broaching machines require a lot of floor space, have a high initial investment cost and offer low flexibility.”
Until about 10 years ago, WEDM was not considered a viable process for full fir tree slot production due to the recast white layer left on components by earlier generator technology. But Welling’s research has shown that WEDM now, with the advent of sophisticated digital generator technology, compares well to broaching in terms of surface integrity and part tolerances – both important in fir tree slots.
So far, Welling’s research has shown through component high cycle fatigue studies that WEDM compares with broaching in terms of component fatigue life, and that WEDM is actually capable of machining fir tree slots with the required accuracy. In addition, Welling says that WEDM offers an advantage when it comes to automation since it offers the process monitoring capabilities necessary to ensure machining quality.
“Furthermore, WEDM does not present the tool wear challenges inherent in broaching,” he adds. “In WEDM, since the tool is the wire that is being unwound from the spool, there’s a new tool being used for every process second.”
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Single platform tool grinding and eroding

The latest version of the Walter Helitronic Tool Studio software for tool grinding now includes integrated functionality for the efficient and effective design, programming and simulation of PCD tool erosion.
Available from Walter Ewag, a member of the United Grinding Group, for all ‘two-in-one’ Walter Helitronic Power Diamond and Diamond Evolution tool-grinding and erosion machines, the new Tool Studio Erosion Wizard-enabled software is said to provide users with a quick and easy route to the selection and real-time simulation of PCD drill, mill and reamer production, incorporating both grinding and eroding operations.

After selecting tool size and geometry, then grinding wheel and electrode ‘package’, the system offers a simulation mode where parameters can be easily changed before tool production starts. Features also include automatic collision control, and geometry and parameter selection for individual teeth.
The new software complements similar Tool Studio functionality for the range of tooling that can be produced/reground on the Walter series of Helitronic tool grinders. This ‘what you see is what you grind’ system has, in effect, now been expanded and enhanced to a ‘what you can grind, you can also erode’ package.
Helitronic Diamond Evolution machines can grind and erode a range of carbide and PCD styles including shank, profile, circular and roll mills, multi-step tools and countersinks, as well as cutting and profile cutting plates. PCD tool programming routines include the erosion of PCD on tool diameters and the production of K-Land, variable spiral and ball-nose gash.
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A&M EDM on course for record sales

A Black Country precision engineering specialist is reaping the benefits of a major investment programme after landing new contracts in the automotive, aerospace and Formula One sectors, as well as parts for automation equipment. A&M EDM, which employs 58 people across its two sites in Smethwick, is heading towards £5m turnover for the first time in its 15-year history after setting its sights on supplying high-value, high-performance components, including the development of engines for unmanned vehicles.
Support from the Manufacturing Growth Programme (MGP) has also helped the company to identify improvements in its marketing activity, strategy and the implementation of a new environmental system that is set to lead to ISO:14001 accreditation shortly.

“We’ve come a long way since I started the business a few doors down, with just two people and a few machines,” explains managing director Mark Wingfield. “Over the past 15 years we have grown into the UK’s largest commercial EDM wire and spark erosion specialist, an achievement that we have built on by adding CNC machining and toolmaking design and manufacturing services.
“We invited MGP to come in and look at our business and how we could increase turnover and manufacturing efficiency,” he adds. “The discussions were great and resulted in the creation of an action plan that focused on our approach to customer relationships, strategy and digital marketing.”
Helen Fortune, manufacturing growth manager at MGP, says: “A&M EDM is keen to seek external assistance to help it get even better and unlock growth. We have identified a number of areas it could improve on and the management team and workforce have embraced them, developing and rolling out a robust environmental management system in just a few months.”
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