But for many people, it comes as a nasty suprise to learn that these machines are not as straightforward as they first seem and that getting them to run consistently and effectively can be more of an art than a science. Too often, they only appreciate this fact sometime after the point of sale and normally well into the period when they expect their production to be in full swing.
The problem stems from buyers being "fooled" into a false sense of security perhaps brought about by the low technology perception of these machines, which is hardly suprising since riveting in it's most basic form has been around for centuries. Also, some Organisations may tend to over estmate their own Engineering capability and take it for granted that their own maintenance team or design team will be able to sort out any problems with these machines. In short, the subject of "riveting" should not be underestimated.
So what should you look out for?
Firstly, begin with the Engineering capability of your supplier. This is not so easy to quantify let alone audit. Sure, you can visit your supplier who, in anticipation of your visit, will no doubt sweep the floor, clean his machines, brief his staff, and ensured his that all calibration certificates and approvals are present and correct. You can conducted a QA Audit, run Dun and Bradstreet checks and draft up a water tight contract so as to apportion liability and lay claim to compensation in a fair and equitable way in the unlikely event of a problem.
But where does the buck stop and will this approach ensure your production goes smoothly? The answers are of course, "with you" and "No". Second hand machinery resellers do not always have the expert knowledge you may expect and so you are really on your own, as the decision maker, to ensure that fundamentally, the equipment you are buying is right for your job. This is a significant difference when you spot buy on the "used" market rather than buying direct from an OEM manufacturer (OEM - Original Equipment Manufacturer).
You can reduce your risk by finding a supplier who has some insider knowledge of the riveting machines he is selling. He may be an ex-machine manufacturer or he may have gianed specialist knowledge from a lifetime spent in the trade, or he may have worked with the machines as a machine operator or maintanance operative for many years. Does your supplier actually know how the machine works because if not then who does?
Pay attention to what kind of questions your potential supplier is asking you. Is he asking lots of questions and trying to get to the root cause of your problem? If so then he is more likely to be able to offer some good advice as to which machine you need and will be far more sympathetic to helping you in the event of future problems. If not, then he is probably simply trying to close a quick sale and you can count on little or no support long term.
There are many riveting methods available including impact riveting, blind riveting, spin riveting, spiralforming, orbital forming, hot riveting, and self piercing riveting. Do you know which is right for your application. If not, someone who knows his business will be able to give you some advise and offer alternatives. On the otherhand, if he looks as confused as you then give him a wide berth!
Obviously, investigate the after sales support on offer and ensure that you can get hold of tools, spares and service to suit your machine model.
Finally, bear in mind that there will be a very good reason why the previous owner of the riveting machine decided to sell. You never know, the riveter may be obsolete, worn out, or have a tendancy to jam up. Often the riveting machines have unique serial numbers which can be traced via the OEM. Give the OEM a call and there's a good chance he will be able to tell you when the machine was originally manufactured and for what application. Very old machines made and those made for heavy duty work will be best avoided.
Tooling and Fixturing
Possibly the most overlooked aspect of owning a riveting machine is the tooling and fixturing. Without well designed and well made tools, your riveting machine is going nowhere.
There are many types of rivets to choose from including tubular rivets, semi tubular rivets, solid rivets, two-piece rivets, break-stem rivets, and eyelets all of which are available in a wide selection of materials (some materials are also more suited to some riveting processes than others). Take some advise from a specialist rivet supplier such as Clevedon Fasteners or Jay Cee Rivets.
Consideration needs to be given as to what type of rivet set (rivet form) to adopt. You can choose from from flat, conical, captured flat, crown, flare, eyelet, stake, crimp, full roll, or part roll.
And then there is consideration as to what kind of tooling to use. Tooling is often dedicated to suit individual applications. Each application can create a totally unique set of design parameters. Notwithstanding the above, the product application itself will influence the tooling design depending upon materials, hardnesses, dimensional tolerances, hole tolerances (where a hole is used for the rivet), product shape, and stability.
There are your own product performance considerations (eg. ability to withstand shear loads, pull off forces, peel tests, vibration tests, fatigue testing, torque testing, electrical conductivity....and so on) which will have an influence on some or all of the above.
It is not always practical to determine the best solution by design due to the large number of options and variables available. Sometimes, the best results are achieved by trial and error or even by accident. If possible, get some samples produced that you can inspect and test even if this means making a small investment to lay down some prototype tooling. The investment will be worth and may even save you money in the long run.