The burr grinder introduction(category, feature, guidance)
Mis à jour : 18 janv. 2020
As a coffee lover, you can't be unfamiliar with the coffee grinders which in charge of the key process of grinding in coffee making. And the blade coffee grinder can grind(blend) but the performance not so satisfactory. You can check our former blog for more information:
A good tool means a lot to coffee. So let me show you our knowledge about the coffee grinders.
The main standard to distinguish them is the power source and the burrs.
So first let's check them by Burrs:
As we have blogs about the blade grinder before, a blade grinder is more similar to a blender and performance is not so good. So we only talk about the burr grinders here in this blog.
What is the burr?
Check the Wikipedia explanation.
Burr is a small cutter used in rotary tools for metalworking.
Burr edge is a deformation of metal wherein a raised edge forms on a metal part that has been machined.
It is the academic description above.
We divided the coffee grinder burr by their shape as below:
1. Conical burr: The conical burr is made up of two different parts. One is a cone-shaped metal with sharpened edges outside. The other is a hollow metal cylinder that has sharpened edges inside. The two parts together will create a V-shaped space that allows beans to go through and grind the beans into preset size.
The beans fall from the upper side by gravity. The burrs swallow the beans mainly gravity.
The gap between the two parts determines the fineness. The particle that comes out is close to round shape. Low noise, shorter time, big fineness range.
2. Flat burr: The flat burrs consist of two similar round-shaped short cylinders that have the sharpened edges on one side. The rotating speed of the burrs is very high compared with conical burrs. So there will be lots of heat created in this process and may have an impact on the quality of the beans and high noise. But this kind of burrs has a great advantage of consistency and only flat can make high fineness powders which are especially needed for Espresso and Turkish coffee.
The flat burr will swallow the beans by centrifugal force and the powder come out from the gap of two burrs. So we adjust the gap between two burrs to control the fineness.
3. Ghost burr: The principle of ghost burr is similar to the flat burr. The only difference is the shape of edges. Ghost burrs have coarse and irregular edges. It is said the performance is between flat burrs and conical burrs. And this kind of burr is very popular in Aisa.
4. Block burr: Honestly I don't think it's proper to call it burr because it doesn't have sharp edges. The grinding elements on it are just the big and small smoothie blocks spread evenly on the round shape discs. It's more crushing than cutting in the grinding process.
The material used in burrs
(1) Pottery: It is a very common material used in the cheap manual grinder and cheap grinders.
Ceramic has advantages like cost-saving, durability.
But also they also have disadvantages that are fragile. They can't bear hard substances like stones mixed with beans. Besides, it's easy to break the burr if the grinder falls down from the table. And it's not as sharp as metal burrs
Price: The ceramic burrs are comparatively cheap compared with the similar shape of the metal.
(2) Metal: It is the material used in professional and commercial use grinders. Because metal
has many advantages over pottery. The big family of metal can be used in different situations. For example, stainless steel, chrome-molybdenum steel, special metal coating.
* High sharpness
* High precision structure (professional use must)
* Impact resistance
* Transfer heat away from beans
* Some alloy material will have excellent performance for grinding.
* Wear out gradually in daily use
Price: The metal burrs are comparatively expensive. Some special alloy burr used in the commercial grinder will be super expensive.
Normally the most common material of burr used is stainless steel. Because it is already good enough and cost-saving.
Let's check them by the power source here
This type of grinder is driven by human power. We need to put our strength on a handle which may have a rotatable disc attached on one end for us to grip. Just rotate the handle and it will transfer power by a mechanism inside to the burr. Then the beans will be ground by the rotating burrs.
The fineness is mainly adjusted by the gap between the inner burr and the outer burr. By rotating the adjustment disc clockwise or anticlockwise, the gap will change and the size of the particle comes out will change too.
Although there are many brands and types of manual coffee grinders, the type of burr is all conical burr. The only difference is the material of burr. Let check:
Type of manual grinder
* The stainless steel cylindrical grinder (Conical burr made of pottery or metal).
* The antique wooden grinder (Conical burr made of pottery).
* the bigger size ROK grinder or similar (Conical burr made of metal).
Price: The cost of the manual grinders are much lower than electrical grinders.
The ceramic burr manual grinder is much cheaper than the metal manual coffee grinder.
2. Electrical coffee grinder
The electrical coffee grinder is one of the most important tools in the cafe or other beverage service shop supplying coffee. It is a grinder that has a motor inside which is connected to the burrs by the mechanism. When using, connect the wire and press the power-on button, The electricity creates the magnetic field to drive the motor. The rotation will be transferred to the burrs. The rotating burrs will cut and crush beans easily. No human strength needed.
All kinds of excellent burrs are used in the electrical grinder.
* Conical burr electrical grinder which demands of a comparatively low-speed motor. It is comparatively cheap among all the electrical grinders.
* Flat burr electrical grinder has a high-speed motor inside to provide high-speed roration which can provide enough centrifugal force to suck beans insides and to push beans through the gap. The flat burr grinder is high consistency electrical grinders which will have a higher value in the market.
* Ghost burr electrical burr has a ghost burr in the grinder which will make grinds has the feature of the above two grinders both.
* Block burr electrical burr is the grinder has a block burr inside for grinding. This type of grinder is not as popular as the above three burr grinders above. But they still share a market and have their fans.
The material used for the grinders
(1)For the burrs
as we talked above, the pottery and metal are common. And they are all used in the electrical grinder burrs. Like a ceramic flat burr grinder, a stainless steel conical burr, or a chrome-molybdenum steel flat burr which is expensive or other burrs with special treatment on the surface which may be crazily expensive.
There are too many to talk about. I will share in the future
(2)For the grinder shell
* Plastic shell: ABS, PP, etc are all used in the cost-saving appliance. The plastic shells are easy to make. Just make by injection machine and the corresponding moulds. The raw material is cheap. By bulk manufacturing, the cost of 1 pcs is extremely cheaper. In the market, you can find many cheap appliances or toys made by plastic that are very cheap. Home use grinder adores this more.
-Advantage: Cost-saving, insulation
-Disadvantage: Not so sturdy, hard, stable and firm like metal shells.
*Steel plate shell with paint: The steel plate is cut, bent and welded together to make a whole shell. Some parts maybe that are plastic or steel is connected to them by screws. The outside of the steel plate is covered with putty powder and paint to prevent rust. It is normally used in the industrial coffee making company which has a very large production. The industrial coffee grinders look very different with home-use or commercial use grinders
-Advantage: Stable, firm, shockproof, durable
-Disadvantage: very heavy, will rust if scraped, high cost
* Stainless steel shell: This material is similar to the steel plate shell with paint but no paint outside. It is just stainless steel outside. And the color is shiny silver or frosted silver. This material is more likely used in industrial coffee grinding, but the production is smaller. The small production industrial coffee grinder and the super big commercial use coffee grinder prefer this material.
-Advantage: Stable, firm, looking professional, shockproof, durable, antirust
-Disadvantage: medium heavy, high cost
* Aluminum alloy shell: Check wikipedia It is an aluminum-based alloy that has many great features over the aluminum. It can be cut and welded to make any shape or structure. The processing steps are similar to other metal. It has the oxide coating outside to protect inside. When scratched, the new oxide coating will be generated automatically. This material is widely used in commercial use coffee grinders.
-Advantage: Stable, firm, looking professional, shockproof, durable, antirust, proper weight.
So if you want to purchase a coffee grinder for home use. I will recommend as below:
Remark: the left is better. We don't have much data for ghost burr and block burr. So here there's no them in the comparison.
1. Want only manual:
Metal manual coffee grinder> Ceramic coffee grinder
2. Want only electrical:
For Espresso/ Turkish:
Metal flat burr electrical grinder> Metal conical burr electrical grinder> ceramic flat/ conical burr grinder> Electrical blade grinder
Metal conical burr electrical grinder> Metal flat burr electrical grinder> ceramic flat/ conical burr grinder> Electrical blade grinder
3. Want better, no care manual or electrical
For Espresso/ Turkish:
Metal flat burr electrical grinder> Metal conical burr electrical grinder> ceramic flat/ conical burr grinder> Metal manual coffee grinder> Ceramic manual coffee grinder> Electrical blade grinder
Metal conical burr electrical grinder> Metal flat burr electrical grinder> ceramic flat/ conical burr grinder> Metal manual coffee grinder> Ceramic manual coffee grinder> Electrical blade grinder
4. Want only flat burr
Metal flat burr electrical grinder> Ceramic flat burr electrical grinder
5. Want only conical
Metal conical burr electrical grinder> Ceramic conical burr electrical grinder> Metal manual coffee grinder> Ceramic manual coffee grinder
Although we can distinguish them by whether it has doser, outlet methods, inlet container type, the shell shape, the blade dimension, they are not the main reasons that we distinguish the coffee grinders. So we don't have further discussion here.
In the future, we will share much more detail knowledge of the grinders in our blog.