Is it advisable to retrofit old machines?

[:is]Why retrofit? Can all machines be retrofitted? At first, the answer is a resounding yes, because the cost-benefit ratio is excellent.

Retrofitting old or outdated machines is highly recommended, because it avoids having to invest in the acquisition of capital goods. In addition, it is easier to pay for, since most companies have a budget for repair and maintenance of their fixed assets. The retrofit –also called rebumping or upgrade– constitutes, then, an investment that avoids the costs associated with the acquisition of a new capital good.

Retrofitting allows avoiding the cumbersome task of getting rid of old or obsolete equipment, allowing the best use of productive space. And, most importantly, you get greater production capacity and profitability. Among other advantages, it allows to maintain the original precision of the machine.

In general terms, we can say that each retrofit is unique and depends on the characteristics of the equipment (type, size, general condition, age, etc.) and the needs and requirements of the client. Next, we will make a brief reference to the general guidelines of the process and the advantages of retrofitting some Metrology laboratory and production equipment.

Coordinate Measuring Machine

Coordinate Measuring Machines (MMC) are the stars in the field of Metrology in terms of retrofit. Its robust construction and the low or zero rate of wear -since they do not have demanding mechanical stresses like a machine tool-, generally make it a structure in excellent condition for retrofitting. The design and construction of the structure in the new CMMs have not changed, what has changed a lot, and with increasing speed, is the electronics. And it is precisely the factor that makes a machine obsolete or outdated.

What does a CMM retrofit consist of? Initially, an exhaustive verification of the machine is carried out and all its electronic components (controller, servodrivers, joystick) are replaced with new components. If necessary –and it is not in all cases–, the measuring rules are changed or old rotary encoders are replaced by optical linear encoders. The measurement head can often be used and reused or it may require the installation of a new one, either fixed or indexable. Within the latter, you can choose between the manual or automatic versions.

Generally, it is necessary to adapt a PC for the chosen measurement software, verify and calibrate. The CMM will work like a new, newly purchased machine.

Advantages after retrofit:

  • The new programming software with an interface for importing from the CAD program makes programming faster and more user-friendly, considerably reducing all times, including setup times.
  • The graphical interface and the calibration wizards mean that maintenance and technical assistance times are considerably reduced.
  • Geometric errors are compensated electronically, which also implies an improvement in working time.

machines Traction Universals

The high cost of acquiring a new large Universal Traction Machine (UTM, for its acronym in English) (30, 50, 100 tons) means that whoever must replace it finds the most convenient solution in the retrofit. This cost is not the only critical factor.

The regulatory requirements, in terms of standardized tests, are increasing. In addition, old or obsolete machines do not have this possibility or the ability to deliver reports in digital format, which today is an essential requirement in the industry.

There are several aspects to consider when doing a retrofit depending on whether the UTM is electromechanical or hydraulic. In turn, they can be mechanical or have electronics. Another variable to consider is that the machine's load box is in good condition.

Depending on the type of UTM, the retrofit may vary. In all cases, it mainly consists of changing and/or implementing suitable and state-of-the-art electronics. This includes, in addition to the software, load cells –type strain gages or others– important both for the measurement of force and for the displacement of the traverse.

In electromechanical it is possible, but not necessary, to have to change the motor and driver assembly.

If these UTM have extensometers, they are verified and calibrated. If you don't have one, you can add one.

The retrofit is finished with the calibration of the equipment with a load cell or certified dynamometric ring.

Advantages after retrofit:

  • No prior preparation is necessary to perform an assay. Once the test parameters have been set, the traverse is automatically positioned to carry it out. At the end, all that remains is to print the report, without the intervention of the operator for its preparation. This is another advantage, since when the operators change, it is not necessary to train them for this function.
  • Cells with strain gages achieve high levels of precision, are maintenance free and mechanical components disappear as in the old dial machines, which required maintenance

Profile Projectors

Projectors, having a long useful life, usually suffer significant wear in mechanical components, due to the use of the table and the verniers. However, its update is simpler than the previous cases and guarantees high performance of the equipment.

The retrofit consists of fine-tuning the optical system, checking the mirrors, lenses, screen, and mechanical parts. In general, in projectors with a lot of wear, the mirror is reluminized and the linear bearings are changed. This first stage is about a "tuning" to make the true retrofit or upgrade, which is carried out with the addition of digital rules with a display or metrological calculator with output to a printer and PC.

This retrofit gathers all the conditions and advantages of the other retrofits, and improves operating performance and times in general, among others. Currently a visualizer can be implemented touch screen.

Machine tools and EDM

For this type of production machines, we must make a separate chapter. The retrofit includes a plus: it involves the addition of electronic reading equipment to know the real position of the axes.

The production machine is subjected to very exhaustive work and with a high workload, which means that certain mechanical components, such as endless screws, guide bearings, slots, etc., begin to take on unwanted play, typical of their wear. . This wear translates into errors at the time of machining the parts.

The incorporation of readers or viewers and digital rulers not only alerts us to wear, but also, by fixing the head directly to the movable axis, we ensure that the movement registered in the displayed axis is the real one and not a false record that we can get to take from the mechanical verniers, as a product of the aforementioned wear.

There are 2 or 3 axis displays. These have the advantage of being able to work with absolute and relative readings. You can also pre-set any determined value and transfer it to the axes. In this case, the costs of this type of equipment for a true upgrade are really low compared to the value of new machinery.

Retrofit advantages:

  • Very low cost compared to the benefit
  • Greater precision
  • Less production time
  • Pre-setting of the reader and data transfer to the axes
  • Possibility of drilling holes in flanges
  • 99 memory steps
  • Concave, convex and ramp milling
  • Ability to do calculations
  • Zeroing at any point

And many more advantages.


This article is not exhaustive, it is an introduction to the retrofit process. Each machine and each client are unique. So each retrofit depends on the evaluation of the machinery, on the one hand, and the customer's requirements, on the other.

The Technical Service Department of ARO SA is qualified to attend queries about this service, and carry out the retrofit of their machines.

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Content originally produced by Wise Marketing for RING SA


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