Hardening Process for Edge of Pencil Sharpener Blade Blanks?

Heat them and place the edge on carbon. It should absorb carbon and become harder and more brittle. Anneal them to sharpen, then temper, then final honing.

heat treating

I would start by looking at the quality at type of steel you are using now, it is obviously too soft.

As for the heat treating, Start off with the data sheet for the steel you are using.

If the carbon content is not high enough, you can not harden the cutting edge cost effectively so you will have to find a better option.

Once you have that sorted out the supplier should be able to provide you with the data sheet for the material which will tell you if and how to harden the material.

Regards,
Sapper

Roy Underhill, of the PBS show The Woodwright's Shop, uses a two-stage tempering process when making cutting tools. In this video, he's making a cutter for a machine that cuts threads into wood dowels. The tempering process begins at the 19 minute mark. Maybe this will help.

http://www.pbs.org/woodwrightsshop/video/2700/2704.html

But he's using some good hard steel.

Which raises the thought, back in my drawing room days, we made knives for sharpening our pencils from hacksaw blades. That material might be a good stock for making blades for the sharpeners.

Many (MOST!) hacksaw blades today are bi-metal; there isn't a lot of the hard steel edge to begin with. If your ground off the teeth, you might very well have nothing left but the softer backing material.

Can you specify the steel for the blades?

Will the heat treating be done in small batches (cottage industry) or all at once? (commercial scale)

How did you temper the steel?

Here is a picture of the sharpener under reference and which I hope will clear the concept. It is the small cutting blade on this sharpener that is required to be hardened to make it reusable without dulling down for a longer period. Next in importance is the small size and the quantity of such blades to be handled in a batch or cycle, whatever.

Another image of a pencil sharpener showing the blade more clearly

Are you working with precuts or with a blade stock which is cut to size in your factory?

If precuts, then Sapper's is the best answer. If blade stock, Passington Green has the right idea... according to what I have read about steel work on the cottage side of industry.

I guess a more detailed explanation of the business model would help.

Nothing is cut in my factory, I don't own one yet.

I am working in a garage;) away from Sappers or Paddington Green, but surely advice from Goblin trio kamikaze is awaited for both the precuts or the blade stock, whichever they can possibly do to fix their katana's!

I am posting this for the information of members here, comments from them will be highly appreciated.

''The Manufacturing Process

Cutting blade formation

• 1 Blade manufacturing processes involve mixing and melting of the components in the steel. This mixture undergoes a process known as annealing, which makes the blades stronger. The steel is heated to temperatures of 1,967-2,048°F (1,075-1,120°C), then quenched in water to a temperature between -76- -112° F (-60- -80° C) to harden it. The next step is to temper the steel at a temperature of (482-752°F (250- 400°C).
• 2 The blades are then die stamped at a rate of 800-1,200 strokes a minute to form the appropriate cutting edge shape. The actual cutting edge of modern cartridge style razor blade is deceptively small. The entire cutting surface is only about 1.5 in (3.81cm) wide by 1 mm deep. This is compared to traditional The plastic portions of a safety razor include the handle and blade cartridge. These parts are typically molded from a number of different plastic resins, including polystyrene, polypropylene, and phenylene-oxide based resins as well as elastomeric compounds. Razor blades are made from a special corrosion resistant blend of steel called carbide steel because it is made using a tungsten-carbon compound. razor blades which are almost 20 times wider and several times thicker. This design creates efficiencies in manufacturing by allowing the creation of a durable cutting surface using very little metal. Because the blade is so small, a special support structure is required to hold it inside the cartridge.''

Read more: How safety razor is made - manufacture, making, history, used, parts, components, structure, industry, History, Design, Raw Materials, The Manufacturing Process of safety razor, Quality Control http://www.madehow.com/Volume-5/Safety-Razor.html#ixzz1ph27rJyr

The blades are then die stamped at a rate of (*)
800-1,200 strokes a minute (SAM?)
13 ... 20 ((21)) Hz ((SI's Fibonacci range ))
_{// (*) -- actually this 1 crossed first the mind ???}

Pencil Talk Lamenting the unavailability of sharpener blades.

.

''Why aren't replacement blades commonly available?

The weak aspect of most portable sharpeners is the blade. The blade may be made very cheaply and be just barely usable a few times, or even if better quality, have become dulled over time. Rust and oxidation may also have had a role.

Yet, in years of frequenting art and office supply stores, I have never seen a replacement blade for sale. Art supply store staff tend to agree that this would be a good idea, but they have no place to order them.

What this means is that portable sharpeners are being sold as de facto disposable items - even fairly expensive ones with glass and metal housings.

I suspect that even a single sharpening dulls many blades, and that the working lifespan of a typical handheld sharpener blade in tip-top condition may be less than that of a single pencil. So there are a lot of blunt sharpeners out there in the world.

Laurentien, a colouring pencil brand that will be known to Canadians (now part of Sanford), states here:

We no longer recommend hand-held sharpeners for any of our colouring pencil lines. These sharpeners usually dull quickly and will chip at the wood instead of shaving the wood.

In the photo are some replacement blades (the KUM Standard 530S) that I ordered from the highly efficient Cult Pens in the U.K. Yikes - replacement blades from overseas. It is a shame that I couldn't buy them locally. But I ordered them as part of a larger shipment, and now wish I had ordered more. It was the only realistic way I could see to keep some favorite sharpeners, like a DUX inkwell, usable over time.

Now some sharpeners truly are disposable - with no ability to replace the blade - but many are attached with a tiny screw, and will take this replacement blade.

Why aren't replacement blades commonly available?

More information here.....

http://www.penciltalk.org/2008/06/replacement-pencil-sharpener-blades

Is it your plan to make and sell replacement blades or to remove them from the assemblies and harden and re-sharpen them? It it would be time consuming to take fresh batches, remove the blades, harden and hone them and the re-assemble them.

If you are working with already formed blades, only the business end needs to be worked. I could see removing a batch of them, picking them up with pliers, heating the business end in a propane torch and then sticking it in some powdered carbon (case hardening it). Then annealing and tempering it (I think this is not the same steel as the razor) with a touch on the stone finish the edge, again, only the business end needs this. It sounds as though it would be cost effective to treat then as throwaways.

Incidentally, I have recently gone back to the old fashioned safety razor.

My object is to make replacement blades in bulk and possibly on a continuous line.

I am considering hardening precut blanks by passing them continuously across the hollow of an induction heating coil.

Manually handling each cut would not be manageable for bigger quantities.

Mazhur,

I'm pretty sure the situation with sharpener blades is the same as with razor blades: it is cheaper to mass produce them, use until dull, and then dispose or recycle, than it would be to sharpen those blades for re-use.

As a metal worker I am very familiar with the problem of handling small items. You must clamp them to do any work, but there's little surface area to do so. Where heating operations are involved, the clamp can also affect the evenness of heating and the results of the process. It is probably possible to design a machine to handle single small blades but it would be costly to build this machine and to operate it, for a very limited potential economic return. A steel working enterprise that had to recycle blades would find it cheaper to melt them and form a new long piece of blade stock to temper, sharpen, etcetera.

If you have a steel working facility (probably not your garage) then you can work with longer pieces of blade stock, sharpen, harden and cut to your specifications. Larger pieces can be handled more readily. From where you are presently, this would require a major infrastructure investment, to have a steel working facility to produce a better sharpener blade, and the question of re-sharpening it is not really addressed because you will not find it economical. Even if you just set out to make a longer lasting sharpener blade, you would have great difficulty making back your investment in the present economic situation, where it is cheaper for a very large steel producer to mass produce blades of moderate or inferior quality, and expect the user to get a new pencil sharpener when the old blade is dull.

If steel was a scarcity, it would be different, even though the blades are small and represent a trivial amount of material. In an economy where you have only one sharpener and must re-use it, or where you insist on doing so, regardless, for your own satisfaction, you could try Passington Green's advice to harden your blade so it holds its edge longer. This should best be done outdoors, for proper ventilation.

Maybe the best answer for you is to design a very convenient blade sharpening tool that makes it easy to sharpen old blades of this size by hand, so it is not a problem even if they are not the best quality steel and must be re-sharpened frequently.

If you use a good steel, something like 4130 or other alloy, you will have a good starting point.

To temper small items, get a steel plate and put it on top of a single-plate electric cooker. The kind they sell in the stores to put on a table for cooking. You could use the wife's gas or electric stove too.

Heat the steel to the proper temperature (use one of those IR thermometers they sell so cheaply now) and then drop each item into salt water (lots of salt).

Now they are too hard and will easily chip. Reheat the steel to the proper tempering temperature and heat the blades. Then drop them in the brine again.

Sharpen to taste.

NOT intending to out-smart OR de-relevance the ... PARENT "Reply"
but competitive process must be simple (*) and RE-use its own "Energy Space" ... e.c.

// (*) -- yet enough sophisticated to for this case ? making http://en.wikipedia.org/wiki/Tungsten_carbide from junk-steel

Fascinating!

So the brine raises the boiling point to the temperature that you want the steel to quench to. It flashes to steam until the steel reaches that boiling point, then slower convection takes over.

Should the brine be preheated so the steel does not drop to ambient temperature too quickly? Should the steel be promptly removed after the boiling noise stops? (This suddenly makes the myth, about quenching weapons into blood, slightly less ludicrous.)

What if only the sharpened edge is submerged? Would only the edge be brittle?

I have so may more questions, and now I'm going to spend time reading about metal hardening and tempering.

First start with right material.I would recommend AISI O1 the alloy steel suitable for knife and tool.Machining to shape and size required then heat to quenching temp.(800-850C) quench into oil to room temp.then tempering at180-200C 2 times then grinding sharpening.You will get the sharpener blade hardness of Hrc60 with good wear resistance

Why not E-Mail KUM at http://www.pencilsharpener.com/email.asp and ask if you can become a US distributor.

thanks ..I checked and they already have an agent in Pakistan. I am contacting them and will try to find out if they could assist.

Reply from KUM

Thank you for your e-mail, but we don't sell replacement blades. We are manufacturer of pencil sharpeners and we need the blades for our own products.

best regards / mit freundlichen Grüßen

Astried Murgan
Sales

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www.pencilsharpener.com

If by chance you find out that you need more carbon in your blades bring them to a cherry red color using a oxy acetylene torch with a carborizing flame ( some black smoke) this will induce carbon into the metal then proceed to harden, temper and anneal to proper specifications.

You will need to make or have made a small die to punch a hole and trim to size. Use a hard spring steel. You will also need a grinding fixture, magnetic to hold the blades. As you grind them they will get blue hot and the coolant from the grinder will quench them. Stone off small burr or use tumbling machine to take off burr. May have to kiss edge with a belt sander with honeing belt.

If you have a choice of materials and you want the cutter edge to remain sharp as long as possible, use tungsten carbide for the cutter blade. You will have to use diamond coated tools to cut and sharpen the blade but no heat treating is required.

I am having a hard time with the whole concept. Why would anyone want to harden blades and replace them in a pencil sharpener that you can buy 72 pieces for $6.75. That is only 9.3 cents a piece. The labor cost of hardening and resharpening a tool that is this inexpensive would be outrageous unless someone designed and automatically operated tool to do the job. I am a tool designer and in my opinion, the tool to do the job would be in the thousands of dollars.

Here is the URL for the inexpensive pencil sharpeners http://www.orientaltrading.com. If you are really interested in this project then you might want to have a tool designed that would do the whole thing automatically.

US9.3cents is hell of a price for a disposable pencil sharpner, atleast for a poor people like the Pakistani's or even the Indians. The point here is not replacing blades but manufacturing them for the stationery industry and to sell them at low price. You can get about half a dozen sharpeners for 10 cents in Pakistan ---but since these sharpeners are much in use ,readily go dull and are lost by people hence the need to increase production to keep pace with the demand.

There are more expensive Chinese sharpeners available in our market but they are expensive. My aim is to produce a low-priced sharpener with good blade in order to compete with the relatively expensive Chinese stuff. There is no reason that I shouldn't be able to do that!!

It is my hope for you that you have inexpensive tool and dye makers in Pakistan. I am also an inventor. Possibly I could just invent a less expensive way to do the job. I would have to think on it a while. I could design the tool for you to be able to harden and sharpen the blades. Are you planning on having people give you their pencil sharpeners to remove and replace the blade, or are you planning on just selling them a new blade for their pencil sharpener?

Nice to know you are an inventor too

I need to harden the precut blades or cut blanks from a continuous sheet, whichever becomes technologically and economically affordable, and sell these blades to sharpener manufacturers or assemblers. This in a way would be a downstream business.

You will have a hard time making any money with this manufacture effort. (IMO)

Having tried several "small" item manufactures over the years, truthfully,
none have really paid. You may get a lot of satisfaction from the "challenge"
if you wish to try, but if it is solely to make money, I would seriously reconsider it.

To give just one example: acting as a buyer, contact several manufacturers
(especially in China, Europe, etc.) requesting a quote for "x" thousand - and be
ready to be amazed! You would (probably) have difficulty in buying the raw material
for the price they make them, package them, and then ship to you.

Another example: to find a rewarding market for such a low ticket item, could take
you years. Ask a few major stationary wholesalers how much they pay for them,
and reflect not only on what price you would need to offer them, to be competitive,
but also the profit margin remaining after deducting your manufacturing costs.

I admit this is all very pessimistic, but it is reality. I have tried so many low ticket
items, some patented, and simply; there is NO money there; IF you can do it !
My latest offering has £1 profit - does it pay? No. Because:

In a small market >20 a day = £20 a day. IN a large market, not competitive. Zero.

Only if you have an "edge," a USP, own the raw materials, peanut cost labour force,
not obtainable (patented) item, etc. do you stand any chance of making money
from such a low ticket item. I can buy a normal small pencil sharpener for 15p from
a retailer - who is probably on 50% (or more) i.e. buying them for 10p. Deduct the
suppliers margin, the distribution costs, the manufacturing costs... what's left?

To test the response, offer a sharpening service and hone the blade edges.
(similar to how they sharpen guillotine blades, and wood working machines, etc.)
You may have to offer it at a price... lower than the cost of a new sharpener?

For a challenge, yes, go for it. For money, I would recommend finding something else?
(Just trying to be helpful before you commit.)

jt.

WHERE I HAVE and HAVE NOT BEEN.

I have been in many places, but I've never been in Cahoots.
Apparently, you can't go alone. You have to be in Cahoots with someone.

I've also never been in Cognito. I hear no one recognizes you there.

I have, however, been in Sane. They don't have an airport; you have to be driven there. I have made several trips there, thanks to my friends, family, and work.

I would like to go to Conclusion, but you have to jump, and I'm not too much on physical activity anymore.

I have also been in Doubt. That is a sad place to go, and I try not to visit there too often.

I've been in Flexible, but only when it was very important to stand firm.

Sometimes I'm in Capable, and I go there more often as I'm getting older.

One of my favorite places to be is in Suspense! It really gets the adrenalin flowing and pumps up the old heart! At my age I need all the stimuli I can get!

Thanks but notwithstanding the pecuniary interest I would like to learn.

Pakistan is an entirely different market than yours and you always have a taker for small things.The big stationers don't care about little things and just import from China,

but there are some people like me who want to learn even if they are not successful.

Nowadays even junk imported from Red Cross is selling like hot cakes....all is made in England or the USA. What you are getting there for 15 p is available here for 2 pence...but surely it has its draw backs---poor plastic, bad blade. But it sells and people want more of it.

You will not disagree with me that a thing being small or big has no meaning in innovative science. you just have to do it for the sake of knowledge or learning and this process must go on.

What do you say about blades being cut from ''funner'' or the steel material rule

dies are made of?? How about cutting blade blanks from it??

Like I said, if it is the challenge (learning) that you wish for, go for it.

Likewise, "all roads lead to Rome" Do it however you like, cut, stamp, etc.

My reply was only about your motive. If the motive is to make money, I have
proved that others can (and do) make low ticket items far cheaper than me.

You may have more success. (I hope) and only occasion you to be realistic,
and do the costings, before you commit and travel too far down the road.

My best wishes. Good luck.

jt.

Thanks a lot, friend, no point for me not to keep the economic factor in mind before embarking on big scale production. After all, economics too is now included in the 'science'' realm!!