Cricket bats are made from willow wood, a variety of White Willow also known as Cricket Bat Willow (Salix Alba).The new cricket bat needs some conditioning before it is used in the competitive environment. In the cricket field the cricket bat needs to withstand constant impact of the ball .For this purpose knocking- in is done. This prevents the bat from cracking and at the same time increases its usable life and gives the maximum performance.
How is Knocking in done? Here are the Steps and Procedure

Oiling:
Initially let us assume that the cricket bat that you purchase arrives in a natural polish finish. The first step involved in knocking-in process is oiling of the cricket bat. Raw Linseed Oil is required to oil the cricket bat. Lightly oil the cricket batl using an open weave cloth or a Chux Wipe. Avoid oiling the splice of the bat (It is the top section of the bat, where the handle joins the bat).

See that there is enough coverage of the oil on the bat. You should be able to see thin film after oiling. Make the bat stand upright and see if the oil is running down. If this happens there is excess oil on the bat so wipe away to see that only a thin film is left out. After this is done lie the bat down horizontally.

Leave the bat overnight and repeat the same procedure but this time use even more less oil as compared to the previous application. Leave the bat horizontally for at least 6 hours.

Now you can be ready for knocking in.

Knocking In
Firstly consider an old leather ball and start softly hitting the front face of the bat with the ball in your hand and the bat on your laps.

See that you are knocking every region of the blade. Work on the edges .Concentrate on the region (lower middle section) where the ball is generally hit by the bat (between 10 to 30 cms (4 to 12 inches from the bottom).After 2 hrs of doing this if you are planning to leave the bat overnight or having a break give a rub on the bat with the lightest oil rubs. I hope that the cloth that was previously soaked in would be enough.

The day after or after the break use a wooden Bat Mallet and gently tap the edges and the face of the blade. Even this time make sure that you cover every region of the blade. Gradually increase the force of your blows. As a result after some time the edges of the bat should show a rounded appearance. 2 hours on this procedure is generally recommended.

After spending these 4 hours go out and bounce the ball up and down on your cricket bat and hit some few catches outside. After 1 hr of doing this then finally head off to nets.

At this stage in the nets do not use new balls or the balls that are not made from leather. Play just defensive strokes for an hour .If your followed the knocking procedure correctly then the ball should not be leaving marks on the face of the blade. If you find any indentions then start the knocking procedure over again.

Now start using new balls in the nets and play some gentle attacking and defensive strokes. Observe your bat and find if there are any indentations left by the ball on the bat. If the bat is knocked in properly there will be only few indentations left on the bat. Like this spend about an hour with the newer balls.

Following this continue using new balls in the nets and watch the face after each stroke. Concentrate on timed shots as opposed to big hitting.

You can follow this net session for a brief time after you get back home.

Following all these steps mentioned above your cricket bat is ready under match conditions.

During the season wipe down the bat with the weave cloth used for oiling. Prior to the oiling process at the time of seasons start and seasons end give your bat a light sanding with very fine sandpaper removing marks and dirty surfaces.

Tips for long life
It is warned not to leave your cricket bat in the hot boot of a car. There is a possibility of doing it during the hot summer days.
Once you get into your change rooms do not take your dismissal out on the cricket bat.
Do not use any cheap cricket balls against your cricket bat.
Cricket bat is not to be exposed to excessive moisture or rain. There is a necessity to always dry your bat immediately if it does get wet. To minimise the amount of absorption through the toe apply the coating that repels the moisture.
It is advised not to over oil your cricket bat.
For your dismissal do not throw your bat or let your cricket bats fly.
Take care of your cricket bat.
Prepare and knock in your cricket bat correctly.
Regularly oil your cricket bat (Use a very light coating once every few months).
Keep the cricket bat in a cool dry location away from excessive heat or moisture.