Posted Wed Apr 3, 2013, 9:17am Subject: Re: Ceramic vs metal grinder - which is better
simply quoting kyle anderson from baratza to answer your question (11+ years of experience in designing coffee grinders):
"Heat and grinding coffee beans: the big misunderstanding
Thermal conductivity of the burrs (i.e. The material they are made from) has NO BEARING on the root cause of heat build up in grinders which comes from a combination of internal friction as the coffee bean is crushed, and from minor friction in the actual cutting of the bean by the burrs. The sharper the burrs ,the less heat is created in the cutting of the bean. The majority of heat creation comes from the crushing of the bean. One could actually argue that the higher thermal conductivity of steel burrs can actually decrease the heat of the ground coffee in small batches. This is because the heat is created IN the bean and is then transferred to the burrs. If the burrs are steel, they will do a MUCH better job of transferring this heat away from the coffee and to the housing of the grinding mechanism. The actual surface temperature of the grinding surface will be similar whether the burr is steel or ceramic, except for that heat which is able to transfer through the burr and away from the coffee. In large industrial coffee grinders, the burrs are mounted to a plate that has water cooling running through it. The burrs conduct the heat away from the beans (and the grinding surface) to the water. A secondary source of heat in ground coffee comes from heat that is stored in the burrs and grinder housing (from coffee ground earlier or immediately preceding) and transferred back into the coffee being ground in the moment."
Bottom-line: Durability is the main difference between steel and ceramic...ceramic will be significantly more durable is not chipped by a rock hiding in coffee beans.
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