Industrial Machinery News

Archive for July, 2009

TWENTY QUESTIONS - What is the best practice for checking metal detectors?

Often industrial metal diction systems are installed on conveyors, pipeline or gravity feed applications.  Once they are installed they tend to be forgotten until an emergency strikes.  To prevent contamination in the food product stream or in any other manufacturing process industrial metal detectors should be tested and used correctly.  Here is a quick check list for any metal detector application.  From this you will begin to understand where your process needs further attention and what areas are working correctly. 

1. Is a metal detector actually being used?
2. Does the metal detector have a self check system set to "fail to safe”?
3. Is an automatic reject system incorporated?
4. For an air operated reject system, is a switch fitted to provide a "fail to safe" situation if the air supply fails?
5. How was the suitability of the system for the application established?
6. Is the product sealed before it is inspected by the detector?
7. If it is not sealed, what is the reason?
8. What precautions are implemented to prevent subsequent contamination?
9. What is the sensitivity standard (ferrous and non-ferrous at least)?
10. How was the sensitivity standard established?
11. Is the standard achieved with the sensitivity sample set in the product so that it passes through the detector on the plane of least sensitivity?
12. How frequently is the detector tested?
13. What was the basis used to establish test frequency?
14. Who is responsible for setting the detector?
15. Who is responsible for testing the detector?
16. Is the test made with metal samples set in the product?
17. Is the reject system tested at the same time as the detector?
18. Is the detector a "computerized unit" providing print-outs of performance? Or if not computerized, is there a written record system?
19. As a minimum are details recorded of Number of rejects,
    1. Frequency and time of system tests
    2. Results of system tests?
20. Where a system test identifies a failure, what action is taken?

Since the discovery of steel modern man has had the ability to create with unlimited potential.  The creation of modern machinery to manufacture and produce a wide range of metal formed products such as guardrails and highway beams, steel stud and zee purlins have enabled companies to manufacture high quality products. 

Many of today’s roads or driveways intersect a highway near to the end of a bridge or other immovable, restrictive features of the highway.  To protect and shield both the end of the bridge and the embankment, a strong post W-beam guardrail curved around the corner is used.  The manufacturing of these interstate or highway guardrails is typically done best with a roll former.  Roll forming equipment is used to bend and ‘form’ the various grooves and profiles in to a flat metal roll.  Compared to other forms of metal bending such as brake pressing or stamping roll forming is much more cost effective and produces a higher quality product.  It should be noted that the terms ‘roll forming’, ‘rollformer’, ‘cold roll forming’ and ‘metal roll forming’ are all interchangeable.  When selecting a roll forming company as with any other capital equipment purchase pricing is typically a less important part of the equation.

As with many other large capital pieces of equipment roll forming machines can be manufactured from very cheap to very expensive.  So how do you know which is the right guardrail roll forming machine for you?  Well, keep in mid several key factors.

1)      How long has the roll forming company been in business?

2)      Is the roll forming machine built for long term reliability?

3)      Are the roll forming stands built to handle repeated bending of metal?

4)      Will the profiles been the same day after day year after year?

5)      Does the roll forming company use FEA (finite element analysis) when designing roll tooling?

6)      Is the roll forming company ISO certified?

These are some important questions to ask yourself before you choose a roll forming manufacturer.  Another area that is very important is how much money will you spend on re-work scrapped or return product?  Often with cheap inexpensive roll forming machines from China you will have to factor in the cost of poor quality parts.  This cost can amount to a lot of money over a short period of time.  It is usually better to start with a quality roll forming machine such as the Samco Machinery roll former.  With in a short period of time you will see how cost is no longer the only factor to use when purchasing a roll former.  Quality, durability and long term re-work costs are some of the key issues to consider. 

Many quality companies use the Samco Machinery (http://www.samco-machinery.com) roll formers when they produce steel formed products.  The output is always of a higher quality and the cost per unit production is lower then less costly poor output machines.

Testing Procedure

When testing a conveyor system normal product flow should be maintained. This will allow for a realistic test of all aspects of the conveyor system. A test package should be created with an imbedded metal test piece, such that it is located in the center of the aperture when passing through the metal detector. This test package should be introduced into regular flow before the metal detector conveyor, and automatically rejected by the reject mechanism.

Options

• Knife edge transfer either using flat belt or Intralox 1100
• Side transfer design
• Wide variety of automatic reject devices
• Low profile design
• Steep incline design
• Hazardous location ratings
• Reject confirm

Reporting Software

A PC software package which would monitor all critical parameters of each metal detector on-line

Automatically generates data for reports

How to test a gravity feed metal detection system for powder and bulk product

Testing Procedure For Pipeline Metal Detectors
 

When using an in line metal detection system you should consider how the system will be tested. There are two basic methods for testing the model 426 pipeline system.

In line insertion
 

This method is the only way to confirm that the whole system is functioning correctly. During a test procedure you would insert a metal contaminate into the product flow. A second valve after the metal detection system should be installed to capture the test product in a holding vessel. If all works correctly you would divert the metal contaminate into the reject bin. If for any reason the system fails you will be able to recover the metal sample in the holding vessel.

Metal Detector Test
 

To determine that the system is detecting metal and operating the reject device, you can pass a metal sample between the product tube and the search head. This method however, does not confirm that metal within the product would be rejected correctly. Method 1 should be the primary testing procedure.

Optional Equipment Found On Most Metal Detectors
 

Reject Confirm
 

Most  metal detectors are capable of automatically sounding an alarm if the reject device fails to operate or operates too slow.

High Temperature Or Pressure

 Teflon pipe coated with F.R.P. for high temperature or pressure applications

 Reporting Software

 A PC software package which would monitor all critical parameters of each metal detector  on-line

Automatically generates data for reports
 

Industrial metal detectors used in the production of food, pharmaceuticals, plastics, confectionary and many other industries are often seen as interchangeable.  Although from the surface a metal detector looks basically the same and operates basically the same its performance can often be extremely different.  

Sensitivity of a metal detector is the repeatable measurement of its ability to detect a known size of tramp metal.  This test sample is generally inserted into the product stream and tested for 100% detection and rejection.  Metal detector manufacturers design and build each unit based on the original customers specifications.  This includes the type of product being inspected.  Here in lies the inherent risk of buying a used metal detector. Most purchasers of used equipment weigh the cost versus performance in determining which direction to go.  With metal detection equipment it is important to understand how performance is measured and what effect slight variations have on true performance.

All metal detector manufacturer’s measure performance using a small sphere or ball of metal.  This is done because a sphere has the same profile regardless of how you present it to the metal detector aperture.  Also this keeps everyone on the same page when measuring base performance.  These spheres are typically measured in millimeters and in 0.5 mm increments.

How does metal detector sensitivity impact used equipment purchasing?

Many companies mandate a metal detectors performance and test to that standard.  When purchasing a used metal detector system it is common to sacrifice on the metal detectors performance to justify the cost.  This can be a critical error and lead to a false sense of protection.  Reducing a metal detectors test sample size say from 1.5mm to 2.0mm isn’t a slight change.  The key is to calculate the volume of the sphere.  The smaller sample has a volume of 1.76mm and the larger sphere 4.18mm.  This means you have reduced your performance by 238%.  This can be catastrophic when real world contaminates enter the production stream.

When buying used metal detectors for any application be very careful when weighing the cost versus performance.  A small savings may end up costing you later.

Roll Forming Machines in India manufacture for the local market producing quality profiles

There are many roll forming machine manufactures around the world.  The question as to what company is the right one to produce roll formed profiles can be tough to answer.   So where do you start?  Looking at a roll forming machine for building corrugated roofing sheets must take in to consideration several key factors.  The machine durability is one of the most over looked elements in the decision making process.  Too often companies choose largely based on price rather then quality.  This often leads to roof panels that are manufactured poorly and require re-work or scrapping.  This will lead to a higher cost per panel when roll formed with a low cost machine.  The roll forming process is very precise even for the most common roll formed profiles and shapes.  The use of sheet metal to make roofing panels has long been the material of choice.  The sheet metal forming process to produce the corrugated profiles utilizes many machines in order to manufacture quality panels.  The tools and dies on these machines are an important part of the overall quality.  Also the strength of each roll tool stand is equally important in producing quality profiles over and over.  Can you imagine using small lightweight roll tooling or stands to bend sheet metal reliably?  It is obvious that you must use a strong machine built by a reputable company who has years of experience.  One such company Samco Machinery, is well known around the world for producing quality machinery for the roofing panel industry.  They also have a roll forming machine division in India to produce local equipment.  If you’re looking for a roll forming line to manufacture corrugated roofing or wall panels I would start with a leader in the market.  Companies like Samco (http://www.samco-machinery.com) manufacture custom machinery that are highly cost effective.  

What are some problem areas for metal detection equipment in food processing?

Conveying System 

Metal Detector Settings

Industrial Environmental Interferences

Product Conditions

Coil handling in the production of roll formed profiles and sections is an integral and important part of the process. The coil is held in a uncoiler or often called a Decoiler and fed in to the flattener or straightener.  The coil is then moved along to a punch and then through the roll forming machine (mill).  This is where the metal is formed in to a specific profile in a continuous form.  At the end of the roll forming machine is a cut off die that shears the metal into specific lengths.  The complete process is highly efficient and requires less labor then other traditional stamping and bending processes.  Uncoilers used in roll forming equipment range in sizes from 3000 lb, 5000 lb, 10000 lb, 15000 lb, 20000 lb, 30000 lb and 40000lb.  The uncolier often includes hold down arms to secure the coil during production.  There are manufactures of reliable quality designed Uncoilers and decoilers that have 5 heads to allow for quick change over’s.  Samco Machinery is one such manufacturer of coil handling equipment.  They are well known around the world for manufacturing equipment used in the metal forming process.  Roll forming steel can be found in many industries such as steel studs for construction, zee purlin, cee purlin, shelving, corrugated roofing panels, automotive parts, highway w-beam guardrails and many more steel profiles.

Material handling equipment is a critical part of any successful operation.  Choosing the right supplier is equally important.  The cost savings of purchasing a quality uncoiler, Decoiler or coil car is quickly returned to the business through greater production through-put and low maintenance costs.  As with any capital purchase many factors impact the final decision on which system to purchase. 

If you are looking for a reliable cost effective uncoiler, Decoiler, coil car or material handling system check out the products offered by Samco Machinery at (http://www.samco-machinery.com)

Testing Procedure

When testing a gravity feed system, it is very important that the test sample travels at the same speed as the product.  In order to verify the response time of the reject gate, metal must be introduced at the same point where the product starts it’s vertical fall.

Allowances must be made to retrieve the test sample, even if it fails to be rejected.  Low air pressure or “sticky” solenoids are typical reasons for failing this test.  Short air lines, high speed solenoids with quick exhaust air fittings, or increased distance between the metal detector and the reject gate, will all improve response time.

The metal detectors “fault” system can be extended to monitor the operation of the reject gate. With this option, hall effect sensors mounted on the reject air cylinder, verify the response time for every detection signal.

Rejected product should be periodically examined to verify that metal contaminants are actually leaving the system.  This will build confidence in your metal detector while isolating possible false rejects.
 

If you need a machine that will improve your speed and accuracy then try a CNC machine when you are getting large jobs done or doing very repetitive tasks. You can get a used one for half the cost of a new one since most individuals wouldn’t want to spend their money on a new one. CNC equipment can be found in woodworking shops or industrial settings. Add them to your collection that includes a milling machine as well.

If you need to drill holes than consider a CNC router. Some of them can hold more than one tool too. This makes it possible to do more than one procedure at a time. This will help you cut back on the tie you spend working and help you become more accurate.

Computer Numerated Control is the full name for CNC. In the 1970’s this technology was first created. These machines are easy to run and operate after they have been initially set up. They also need to be set up correctly and programmed before they are operated.

They can be made so you can drill a hole automatically. This can be much more accurate and quicker than manual drilling. You will get more uniform results. If you have a large job that needs a lot of drilling then this can be a good choice for you. You might get more inconsistent results when you are doing manual drilling and if the operator gets tired.

If you want a good thing to cut wood with then try a CNC lathe. You can buy one that ranges from 15-40 horsepower. You will choose the lathe power you need depending on the type of wood you use. You can get a model that comes with more than one mode. You can one that is totally manual or CNC. You can rig each machine for your individual project.

If you want the best in milling technology then try a Bridgeport mill. You can find a mill in both a small shop or a large one. If you want a mill that will last forever than try a Bridgeport mill. They are very pricey and more so than most people can afford.

A CNC mill use a special type of instrument that uses a combination of robotics and computer programming. You will get great results better than anyone could ever want. These are the kind of mills that the airline companies use. The CNC decides which tool is need for an operation and changes as it goes.

Since CNC equipment is so pricey it means most people can’t afford it. If you get a used machine you may find that you can afford it. You may be able to save about half on a used machine compared to a new one.

Being really passionate about cnc machinery and woodworking tools, Greg Hansward authored different summaries in this specific area. With his detailed writings on cnc machines and tools and cnc machinery the reviewer showed his deep knowledge on the topic.

 
By Greg K. Hansward