Oct 19, 2012
A strategic overview of the production turning industry in SABack
DURBAN|South Africa|Electronics|Metal Removal Rate|Product Manufacturer
© Reuse this
A vast number of industries, including the automotive, appliance, electronics, bathroom fittings and other industries, and products make use of turned components, says machine tools manufacturer FAS Machine Tools CEO Peter Frow.
In a research paper written by Frow, he points out that some of these components are made in-house by the product manufacturer, while others are subcontracted to specialist repetition turning ‘job shops.’ The component type and size vary enormously, as do batch sizes – anything from ten to hundreds of thousands.
“Where batch sizes increase above 100 and particularly above 1 000, the components will typically be made on one or other type of production lathe,” he states.
A production lathe is any lathe where the tool movements are achieved by some automatic means. Thus, once set, they can produce components without any direct operator action, except for loading the raw material.
“In the production turning stakes, it is important to select the best machine for the job.
“The best machine is the one that yields the lowest cost for a particular component and a particular batch size,” says Frow.
Generally speaking, the production turning industry uses two distinct types of production lathes – Cam automatic lathes and computer-numerically controlled (CNC) lathes.
The paper highlights that the design of the cam automatic lathe was pioneered over a hundred years ago and it uses cams for achieving tool movements. The lathes are characterised by fast cycle times and long set-up times.
Further, the paper states that CNC lathes were developed in the seventies, initially as hard-wired numerically controlled machines. They soon incorporated microprocessors, hence the term CNC. These lathes have relatively long cycle times, compared with cam-operated lathes, especially for smaller components, but are far more user-friendly and have relatively short set-up times.
“Within these two broad categories, production lathes can be further broken down into various subtypes (see Figure 1).
“The diagram illustrates that there is usually something of a trade-off between cycle time and set-up time.
“Cycle time is a function of the metal removal rate (MRR) of the different tools, the number of tools that can be made to work simultaneously on the work piece, and the time taken for nonproductive or idle operations, such as the feeding of material and indexing of tools.
“Thus, to optimise the cycle time, one must maximise the MRR, maximise the number of tools working simultaneously and minimise the duration of idle operations,” says Frow.
He points out that the cam-operated multi-spindle lathe (Type A, Figure 1) works on six components in various stages of completion at any one time. Thus, it has as many as 12 tools cutting simultaneously.
“Amazingly, this type of machine was developed in the late nineteenth century and still produces the quickest cycle times of any production lathe.
“However, South Africa has less than 150 of this type of machine in regular operation.
“The greatest number (estimated at 2 500+) of cam automatics in the country, are of the single spindle type (Types B, C, & D),” he says.
Frow notes that these machines can typically have four tools working simultaneously. They make extensive use of the ‘plunge forming’ technique, where tools having a particular shape are advanced into the work piece along an axis perpendicular to the spindle axis.
“By contrast, CNC lathes use single point tools and generate the required shapes with a digitally programmed tool path. Form tools can generally be applied at the same time that end working is taking place. This technique is known as ‘overlapping’.
“In order to select the best machine for a particular application, one should plot the cost-effectiveness curve for each machine being considered. Figure 2 would be a typical set of curves for a component of less than 40 mm in diameter made from bar stock.
“Other things being equal, the batch size represented by X would be the point at which it would be more cost effective to make the component on a cam automatic than a CNC lathe. Batch size Y would be the point at which a multi-spindle would become the better choice,” says Frow.
He points out, however, that other things are not equal: In particular, there is a dwindling pool of tool setters with the skills necessary to set cam automatic lathes. Each job requires a set of job-specific cams. The number of persons capable of designing optimum cams has also shrunk.
“There is thus a tendency to run jobs on CNC lathes despite their longer cycle times where the cost effectiveness curves would suggest otherwise.
“The great majority of CNC lathes in the country are of types J and K, although there are a fair number of type H lathes.
“Viewed at a macro level, the net effect of this is a tendency to drive component prices upward, making South Africa less competitive in a global market,” says Frow.
He notes that imported type E CNC lathes have cycle times comparable with cam automatics, but unfortunately are priced such that one can purchase about three type J machines for the same figure.
Further, he says that, despite fierce competition from the East, South Africa has CNC lathe manufacturers. “Efamatic in Gauteng produces a range of type J machines, while FAS Machine Tools in Durban manufactures a type E multi-slide machine with cycle times that more than match those of equivalent cam automatics.”
Edited by: Chanel de Bruyn© Reuse this Comment Guidelines
Other Machine Tools News
Industrial products supplier Dowson & Dobson (D&D) Industrial expects its distribution agreement with industrial products supplier Pneumatic & General Supplies for Richards Bay, in KwaZulu-Natal (KZN) to expand its reach to industries that include the coal,...
A modern computer numerically controlled (CNC) turning machine must be productive, flexible and easy to operate, says local machine tools distributor Retecon MD Hans-Peter Neth. He tells Engineering News that the new monoBlock and CTX ecoline series of machine tools...
Professional sawing and drilling contractors have shown significant interest in the new Titan high-frequency wall saw, which is apparent in the several orders pending final financial clearance by companies, diamond tools and equipment manufacturer and supplier...
Updated 25 minutes ago The Department of Science and Technology (DST) is very happy with the success of the South African Research Chairs Initiative (SARChI), DST Director General Dr Phil Mjwara told Engineering News Online. He was interviewed after Deputy President Kgalema Motlanthe...
Updated 1 hour 58 minutes ago The South African Revenue Service on Friday hiked the import duties of certain screws, bolts and fasteners to level the competitive playing field for local producers. The International Trade Administration Commission of South Africa (Itac) said in a statement that...
Updated 2 hours 1 minute ago The second Africa CEO Forum, which is expected to attract more than 700 African and international CEOs, financiers and business leaders, will include core themes on Africa’s competitiveness enhancement, the “Africapitalism paradigm” and the digital revolution....
Recent Research Reports
Automotive 2014: A review of South Africa's automotive sector (PDF Report)
The report provides insight into the business environment, the key participants in the sector, local construction demand, geographic diversification, competition within the sector, corporate activity, skills, safety, environmental considerations and the challenges...
Construction 2014: A review of South Africa's construction sector (PDF Report)
Construction data released during 2013 hints at a halt to the decline in the industry during the last few years, with some commentators averring that the industry could be poised for recovery. However, others have urged caution, noting that the prospects for a...
Electricity 2014: A Review of South Africa's Electricity Sector (PDF Report)
This report provides an overview of the state of electricity generation and transmission in South Africa and examines electricity planning, investment in generation capacity, electricity tariffs, the role of independent power producers and demand-focused initiatives,...
Defence 2013: A review of South Africa's defence industry (PDF Report)
Creamer Media’s 2013 Defence Report examines South Africa’s defence industry, with particular focus on the key players in the sector, the innovations that have come out of the defence sector, local and export demand, South Africa’s controversial...
Road and Rail 2013: A review of South Africa's road and rail infrastructure (PDF Report)
Creamer Media’s Road and Rail 2013 Report examines South Africa’s road and rail transport system, with particular focus on the size and state of the country’s road and rail network, the funding and maintenance of these respective networks, and the push to move...
Liquid Fuels 2013 (PDF Report)
Creamer Media’s 2013 Liquid Fuels report examines South Africa’s liquid fuels market, focusing on the business environment, oil and gas exploration, the country’s feedstock supplies, the development of South Africa’s biofuels industry, fuel pricing,...
This Week's Magazine
A structured approach, wherein managers personally engage at each level of the project, is necessary to mitigate delays to the workflow on mega construction projects, says State-owned Eskom Kusile power station projects GM Abram Masango. The 4 800 MW Kusile power...
Construction of transmission lines to evacuate power from a regional hydroelectric project in East Africa, which was hanging on the balance following the withdrawal of financing by key partners, is now back on track. After six months of uncertainty, the African...
Three Memorandums of Understanding (MoUs) were signed between South African and Malaysian companies at the Malaysian High Commission in Pretoria on Friday. These MoUs are part of the indirect offsets programme South Africa is providing in return for Malaysia’s...
The South African new vehicle market may well dip to 640 000 units in 2014, says Toyota South Africa Motors (TSAM) sales and marketing senior VP Calvyn Hamman. This is the first prediction that anticipates a drop in the market. To date economists and industry bodies...
Nissan will re-enter the South African minibus taxi industry in March, when the new NV350 Impendulo goes on sale. The 16-seater has been specifically tailored to meet the terms of government’s Taxi Recapitalisation Programme, which aims to replace South Africa’s...
Next ArticleNew range of industrial screwdrivers available in SA