With X-ray machines becoming more capable, more reliable and less expensive – and with retailers constantly tightening their specifications to improve customer confidence – I’m seeing a surge in manufacturers upgrading their inspection capabilities. The question is – is now the time for you to switch to X-ray?
Firstly let’s take a quick look at the pros and cons of the two technologies, then I’ll share with you the 13 killer questions that I’ve learned throughout my career will get you the best solution. If you ask these 13 questions of your production, technical, engineering, hygiene and financial teams, I guarantee you’ll get a better outcome than you would have otherwise, and you’ll save yourself lots of time and hassle.
Making the right choice for you depends on many factors – product, product size, speed, contaminant type and level, packaging etc. – so there is no right or wrong answer, it’s whichever suits your product and application best.
It was 1948 when the first metal detector was installed in the UK, and from then to today, metal detectors have been used as the last line of defence for the food, beverage and pharmaceutical industries. There are two main factors driving this popularity – cost and reliability; they do what they do really well, and they do it cheaply.
Metal Detection ADVANTAGES
So now let’s look at the disadvantages:
Metal Detection DISADVANTAGES
The obvious disadvantage of metal detection is that it can only detect metal (the clue’s in the name) – so as soon as you want to screen for other type of contaminants, then your decision’s been made for you.
Contaminants come in all forms, and are generally introduced in one of two ways: either brought in with the product, or as a result of a failure in the manufacturing process. An organic product from the fields would be prone to grit, stone, insects, glass and other debris being grown into it, whereas a product that requires more complex manufacturing processes would be more likely to be contaminated by in-house contaminants. The golden rule is that the more technical processes a product has to go through, the more potential there is for contamination.
There are a few points in the table above that should seem obvious (ie. stray metal objects and magnetic fields near the device will alter its performance), but there are some more subtle points: a large product with a large machine head will have reduced sensitivity for finding smaller metallic parts, and that “polar” molecules such as water and fat can line up in the presence of the magnetic field to affect the performance of the unit.
X-ray has some obvious advantages over metal detection: not only will they detect metals, they will also detect glass, stone, calcified bone and some chlorinated plastics (Viton) – and they can be also used for quality testing. The latest X-ray machines will detect broken or missing products/ components, determine product mass, analyse the fat content in meats, inspect the final product seal, and measure recipe control. All of this can be done either in or out of its final packaging – whether the products are canned or in a jar, pouch or box.
It’s not all plain-sailing though, so let’s start by looking at the disadvantages of X-ray inspection:
X-ray Inspection DISADVANTAGES
When you compare X-ray inspection machines to metal detectors, there are three main categories of disadvantage: 1. the machines are physically bigger, 2. they’re more expensive in various ways and 3. they can’t just see anything.
That the machines are physically bigger can have a knock-on-effect in cost; bigger machines may mean your production lines need to be moved further apart to maintain safe-working distances between them. Depending on your environment this can be anything from merely inconvenient if you’re lucky, to a major project if your facility has been designed to house a certain layout of inline equipment.
There are some direct costs too: when you’re introducing X-rays into your site, you’ll need to invest in an RPA (Radiographic Protection Advisor), as well training, annual certification and the creation/ maintenance of procedures for your team. If you need to upgrade your product handling to do the presentation properly, then that will be a cost, too. X-ray machines rely on the product being presented for inspection uniformly, unlike metal detectors, which will accept products of differing sizes and speeds through the detection head without causing spurious rejects.
Whether or not you can detect, via X-ray, a particular contaminant in a particular product is ultimately determined by the Periodic Table (Remember that from school??). The Periodic Table tells you the atomic numbers of each element, and X-ray inspection works by being able to ‘spot the difference’ between different items with different atomic numbers. The larger the difference in atomic numbers – the easier it can be detected, the more similar the numbers are, the harder they are to differentiate. Because of this, it maybe that certain contaminants are really easily spotted in your product, or they might be literally impossible to detect.
In some markets, X-ray machines have a poor reputation for being unreliable, expensive and not able to do what they say they can. Whilst some of that criticism is fair for the past, I can see that things are changing rapidly. The technology is now 30+ years old and has had a time to mature and develop.
The primary criticism you often hear is the poor life of X-ray generators. It’s my opinion that, whilst that used to be a valid complaint, things are different now. I’d wager most, if not all, of those failures were caused by the X-ray tube overheating, so the poor life came from two factors: poor quality components and poor quality start up and shut down routines. If you want to get the ultimate life, you have to specify a high-quality tube, follow the step by step instructions for “first time use, start-up and shut down procedures” and make sure that the cooling system filters are cleaned regularly, with the cooling system remaining in full working order.
As I’ve said in my Euroscan is now open blog post – I specify and use Sapphire machines for all of my applications because of the quality of the Cheyney components inside them. I’ve seen hard data from Cheyney of machines in the field where the generator is still going without replacement after 20 years. Cheyney say that if you use the right generator and you follow the right service procedures, there’s no reason that the generator shouldn’t outlive the life of the machine. I’d say that’s a case where reputation needs to change.
Finally, before we move onto the 13 questions you need to know, let’s look at the advantages of X-ray inspection:
X-ray Inspection ADVANTAGES
|Inline X-ray inspection machines can:
*Note – The mass measurement is not a legal weight in accordance with Trading Standard’s Weights and Measures, but it’s accurate!
Clearly, the latest X-ray inspection machines have a lot of additional functionality compared to a metal detector; and as the technology and detection algorithms improve, the functionality improves, too – with no more increase in physical size. Of course, the trade off for the functionality is cost: some standard X-ray machines may only be 1.5x the cost of a metal detector, but if you’re after a truly bespoke machine for a bespoke application, you can be well into six figures to have something that’s ready for the rigours of a production environment.
It ultimately comes down to your product and the specifications you’re trying to meet; can you benefit from one or more of these features, and is that worth the cost?
The top 13 questions to ask yourself when choosing an inline inspection machine.
With all of that said and done, I’m ready to show you the 13 questions that I use when trying to decide the right machine for an application. Some of these questions might surprise you, because they’re more about you than the machine, and some of them may make you realise that other parts of your processes need work. That’s what these questions are for. They’re designed to make you and your team think, and work together to get a great solution. Answer them, and you’ll save yourself a lot of time and hassle.
Here are the questions:
1. Why: Why are you looking at changing from metal detection to X-ray?
The first question is the most fundamental one – why are you considering X-ray inspection? Is it something that you’re doing proactively to protect your products, your brand name, your position in the market? Is it to better yourself and your processes — or is it a requirement forced on you by a customer?
In my experience, companies that are proactively investing to improve their processes tend to make better overall decisions than those that are having their “hand forced” by a customer. Of course, 99% of the time, it’s purse strings that will have the biggest effect on the final results; but companies that go through the process to better what their customer’s asking for (even if they don’t tell the customer!) can often get a much better result for not much more money.
2. Downtime: What %age of downtime are you experiencing on your detection devices?
What downtime are you currently experiencing, and what would you (realistically) like it to be?
Some people reading this will know their last week’s stats off the top of their head, whereas other factories don’t even measure it at all. Answering this question will help you zone in on your needs and begin the process of getting there, if you aren’t already.
At the end of the day, if your stats aren’t currently what they should be, you need to look at why – and decide how a new machine is going to solve your problems. For example: if your downtime is currently 60% then there must be an issue with the machine being either not fit for purpose, not being maintained properly or not having been set up properly. Each of these factors needs to be addressed individually.
One good thing about X-ray machines is that they’ll give you a Real-Time Display of everything you could ever want to know: the exact uptime, downtime, throughput, contaminant frequency, etc. so that you’re always up-to-date and there’s never any argument. How you use that information is another thing entirely…
3. Contaminant size: What size contaminants are you running at?
Next you need to know what size of contaminants you’re currently detecting – and what would be the best-case-scenario for your product and customer?
If the customer asks you for 1.5mm, and the technology can get you to 0.8mm, then you’re in a great situation. I can tell you from experience that when the customer comes to you to say they’ve had a contaminant problem on a batch, there’s no better feeling than being able to say “here’s our results for the last 12 months, we’ve been running under your spec. and here’s all the photos from the batch you’ve mentioned”. It makes the conversation a lot easier, and you present yourself in the most professional way.
4. Contaminants other than metals: What would you like to find, and what are causing you (or your customer’s) issues?
This question is asking you to think through your processes to decide where the problems can arise.
If you take the example of the food industry, generally the main contaminants are: plastics from bags, aprons and gloves, wood and cardboard from pallets and packaging, stone brought into the process from an external ingredient, or glass from an in-house failure in procedure, or accidental breakage. So, perhaps surprisingly, most of the contaminants aren’t metallic, they’re things like these.
…and it’s not just about machines – I’ve seen more than one case where production managers in FMCG, every Monday morning, go around the factory and pick up all the bits of potential contaminant that they find left over from the weekend: bits of apron, nuts and bolts, rubber seals, bits of knives. They then stick all these contaminants onto a notice board in a high-traffic area and gather up the staff so that they can see and discuss what the issues are. Procedures like that can make a big difference to your end result.
5. Throughput: What speeds would you like to run at?
It ought to go without saying, but the machine you choose needs to process the right volume of product, for the right contaminant, at the right speed.
In every inline process, there’s always a limiting factor, the important thing is to think things through carefully and then specify the machine so that it’s not the critical path. I’ve seen a case where one part of a factory orders a number of new X-ray machines before the other part carries out the line upgrades – only to find that when those upgrades are complete, the X-ray machines themselves were holding everything else back.
I would generally advise adding 25-50 percent extra throughput to your specification so that the machine is future proofed. That way you’ll not be limited by our machinery in the foreseeable future – you don’t want a machine that’s going to be too slow in two years time.
6. Data collection and display: What would you like to see and from where?
Each part of your manufacturing will want so see different things: Technical will want to see the full paper trail including photos of the rejected products; the Production Management will want to see how fast the line is running. These things can be viewed on the machine or via ethernet into the office.
Modern X-ray machines have got an amazing ability to log everything and display it however you want. If you think about what you want and where you want it, then you can get it right.
7. Ease of use: What concerns do you have about how easy the machine is to operate?
A machine that’s difficult to use slows everything down – and ultimately costs money in lost production and staff training.
We’ve all come up against a machine that has a complicated setup procedure; it takes forever to restart after a product change/ calibration/ QA check/ parameter change – thus losing precious production time. When it’s an inline machine you need changes to be quick, you want to have two or three touches whilst you change a parameter or product. You don’t want to have to stop the machine, take it off line, spend 5 minutes changing something – because that’s all production time lost.
8. Uptime performance: What realistic %age are you looking to run at?
Many factories don’t measure downtime, but some of those that do, also measure uptime performance. Whilst downtime performance is about the amount of time the machine is running, uptime performance is how efficiently it runs when it runs. Those of you that are passionate about line optimisation will be able to find some useful data here.
9. Speed of a product changeover: What is the allotted time for a changeover of product and would you like it to be easier and shorter?
Do you know the current changeover times for your line(s)? Do you want them to be faster or are you happy the way they are? You should be allocating a specific amount of time to change: for example, if you’re going from allergen to non-allergen you may need a full clean down, not just a blast of air – how long does each of those take?
When you’re choosing between machines, one may take longer than the others, so you need to ask the question to find out.
10. Product quality: What could you be looking for that you are currently not looking for?
Let’s stick with the food industry example that I’ve used throughout – which of the new features of X-ray could you use to improve your product?
Has the product got the correct amount of filling, and is it evenly distributed within the product? In multipacks of your product are there any items damaged or missing? All of these recipe control features are available in X-ray machines.
X-rays machines are far more versatile than a metal detector in this respect – so what do you want to do? What could you be looking for, and will your product allow it?
11. Rejected Products: How do you handle them?
How are your rejects currently handled and how long does it take? Are your rejected products reintroduced into the production run, or re-checked at the end of the run? Can that time be saved?
12. Cleaning: How long does it take for the machine to be fully cleaned?
And is that an issue for you? Again, this is a factor that many production environments don’t fully account for.
13. Physical interruptions: What could affect the smooth running of the machine?
Are there any factors that could influence the smooth running of the inspection device? Are Hygiene going to soak it through daily? Will it be bumped into by passing traffic? Is it subject to high/low temperature cycles? Will it be moved from its inline position? Is there enough space around the device to work and use it safely?
All of these potential risks, and more, need to be assessed to get the best out of the device.
…and because I like to under-promise and over-deliver – here’s an extra bonus 14th question:
14. The magic wand: If you could wave a magic wand, what would you point it at in your process and why?
…and is that easily solved?
This question can be telling because it often elicits different answers from different people. Obviously different departments are focussed on different things: Production may say it doesn’t run fast enough, Technical may say it doesn’t give they information in they format they require, Hygiene may say it’s difficult to strip and clean, and Engineering may say it’s difficult to work on and get spare parts for.
Asking this question, and doing something with the answers, can be the start of some real improvements.
X-ray machines are becoming cheaper and more reliable, and they offer far more functionality than metal detectors. As a result, it may well be time for you to consider upgrading. If you are thinking of making the leap, then do consider some of the questions I’ve asked (above) to make sure you really get the solution that’s right for you and your application.
If you are thinking of upgrading to X-ray, for whatever reason, and you’d like some advice, please do give me a call. I can certainly help you go through the process that I’ve just described to find the solution that’ll suit you best.
You can find my phone number and e-mail contact here.